Source code: Lib/socketserver.py
The socketserver module simplifies the task of writing network servers.
There are four basic concrete server classes:
This uses the Internet TCP protocol, which provides for continuous streams of data between the client and server. If bind_and_activate is true, the constructor automatically attempts to invoke server_bind() and server_activate(). The other parameters are passed to the BaseServer base class.
This uses datagrams, which are discrete packets of information that may arrive out of order or be lost while in transit. The parameters are the same as for TCPServer.
These more infrequently used classes are similar to the TCP and UDP classes, but use Unix domain sockets; they’re not available on non-Unix platforms. The parameters are the same as for TCPServer.
These four classes process requests synchronously; each request must be completed before the next request can be started. This isn’t suitable if each request takes a long time to complete, because it requires a lot of computation, or because it returns a lot of data which the client is slow to process. The solution is to create a separate process or thread to handle each request; the ForkingMixIn and ThreadingMixIn mix-in classes can be used to support asynchronous behaviour.
Creating a server requires several steps. First, you must create a request handler class by subclassing the BaseRequestHandler class and overriding its handle() method; this method will process incoming requests. Second, you must instantiate one of the server classes, passing it the server’s address and the request handler class. It is recommended to use the server in a with statement. Then call the handle_request() or serve_forever() method of the server object to process one or many requests. Finally, call server_close() to close the socket (unless you used a with statement).
When inheriting from ThreadingMixIn for threaded connection behavior, you should explicitly declare how you want your threads to behave on an abrupt shutdown. The ThreadingMixIn class defines an attribute daemon_threads, which indicates whether or not the server should wait for thread termination. You should set the flag explicitly if you would like threads to behave autonomously; the default is False, meaning that Python will not exit until all threads created by ThreadingMixIn have exited.
Server classes have the same external methods and attributes, no matter what network protocol they use.
There are five classes in an inheritance diagram, four of which represent synchronous servers of four types:
Note that UnixDatagramServer derives from UDPServer, not from UnixStreamServer — the only difference between an IP and a Unix stream server is the address family, which is simply repeated in both Unix server classes.
Forking and threading versions of each type of server can be created using these mix-in classes. For instance, ThreadingUDPServer is created as follows:
The mix-in class comes first, since it overrides a method defined in UDPServer. Setting the various attributes also changes the behavior of the underlying server mechanism.
ForkingMixIn and the Forking classes mentioned below are only available on POSIX platforms that support fork().
socketserver.ForkingMixIn.server_close() waits until all child processes complete, except if socketserver.ForkingMixIn.block_on_close attribute is false.
socketserver.ThreadingMixIn.server_close() waits until all non-daemon threads complete, except if socketserver.ThreadingMixIn.block_on_close attribute is false. Use daemonic threads by setting ThreadingMixIn.daemon_threads to True to not wait until threads complete.
Changed in version 3.7: socketserver.ForkingMixIn.server_close() and socketserver.ThreadingMixIn.server_close() now waits until all child processes and non-daemonic threads complete. Add a new socketserver.ForkingMixIn.block_on_close class attribute to opt-in for the pre-3.7 behaviour.
These classes are pre-defined using the mix-in classes.
To implement a service, you must derive a class from BaseRequestHandler and redefine its handle() method. You can then run various versions of the service by combining one of the server classes with your request handler class. The request handler class must be different for datagram or stream services. This can be hidden by using the handler subclasses StreamRequestHandler or DatagramRequestHandler.
Of course, you still have to use your head! For instance, it makes no sense to use a forking server if the service contains state in memory that can be modified by different requests, since the modifications in the child process would never reach the initial state kept in the parent process and passed to each child. In this case, you can use a threading server, but you will probably have to use locks to protect the integrity of the shared data.
On the other hand, if you are building an HTTP server where all data is stored externally (for instance, in the file system), a synchronous class will essentially render the service “deaf” while one request is being handled – which may be for a very long time if a client is slow to receive all the data it has requested. Here a threading or forking server is appropriate.
In some cases, it may be appropriate to process part of a request synchronously, but to finish processing in a forked child depending on the request data. This can be implemented by using a synchronous server and doing an explicit fork in the request handler class handle() method.
Another approach to handling multiple simultaneous requests in an environment that supports neither threads nor fork() (or where these are too expensive or inappropriate for the service) is to maintain an explicit table of partially finished requests and to use selectors to decide which request to work on next (or whether to handle a new incoming request). This is particularly important for stream services where each client can potentially be connected for a long time (if threads or subprocesses cannot be used). See asyncore for another way to manage this.
This is the superclass of all Server objects in the module. It defines the interface, given below, but does not implement most of the methods, which is done in subclasses. The two parameters are stored in the respective server_address and RequestHandlerClass attributes.
Return an integer file descriptor for the socket on which the server is listening. This function is most commonly passed to selectors, to allow monitoring multiple servers in the same process.
Process a single request. This function calls the following methods in order: get_request(), verify_request(), and process_request(). If the user-provided handle() method of the handler class raises an exception, the server’s handle_error() method will be called. If no request is received within timeout seconds, handle_timeout() will be called and handle_request() will return.
Handle requests until an explicit shutdown() request. Poll for shutdown every poll_interval seconds. Ignores the timeout attribute. It also calls service_actions(), which may be used by a subclass or mixin to provide actions specific to a given service. For example, the ForkingMixIn class uses service_actions() to clean up zombie child processes.
Changed in version 3.3: Added service_actions call to the serve_forever method.
This is called in the serve_forever() loop. This method can be overridden by subclasses or mixin classes to perform actions specific to a given service, such as cleanup actions.
New in version 3.3.
Tell the serve_forever() loop to stop and wait until it does. shutdown() must be called while serve_forever() is running in a different thread otherwise it will deadlock.
Clean up the server. May be overridden.
The family of protocols to which the server’s socket belongs. Common examples are socket.AF_INET and socket.AF_UNIX.
The user-provided request handler class; an instance of this class is created for each request.
The address on which the server is listening. The format of addresses varies depending on the protocol family; see the documentation for the socket module for details. For Internet protocols, this is a tuple containing a string giving the address, and an integer port number: ('127.0.0.1', 80), for example.
The socket object on which the server will listen for incoming requests.
The server classes support the following class variables:
Whether the server will allow the reuse of an address. This defaults to False, and can be set in subclasses to change the policy.
The size of the request queue. If it takes a long time to process a single request, any requests that arrive while the server is busy are placed into a queue, up to request_queue_size requests. Once the queue is full, further requests from clients will get a “Connection denied” error. The default value is usually 5, but this can be overridden by subclasses.
The type of socket used by the server; socket.SOCK_STREAM and socket.SOCK_DGRAM are two common values.
Timeout duration, measured in seconds, or None if no timeout is desired. If handle_request() receives no incoming requests within the timeout period, the handle_timeout() method is called.
There are various server methods that can be overridden by subclasses of base server classes like TCPServer; these methods aren’t useful to external users of the server object.
Actually processes the request by instantiating RequestHandlerClass and calling its handle() method.
Must accept a request from the socket, and return a 2-tuple containing the new socket object to be used to communicate with the client, and the client’s address.
This function is called if the handle() method of a RequestHandlerClass instance raises an exception. The default action is to print the traceback to standard error and continue handling further requests.
Changed in version 3.6: Now only called for exceptions derived from the Exception class.
This function is called when the timeout attribute has been set to a value other than None and the timeout period has passed with no requests being received. The default action for forking servers is to collect the status of any child processes that have exited, while in threading servers this method does nothing.
Calls finish_request() to create an instance of the RequestHandlerClass. If desired, this function can create a new process or thread to handle the request; the ForkingMixIn and ThreadingMixIn classes do this.
Called by the server’s constructor to activate the server. The default behavior for a TCP server just invokes listen() on the server’s socket. May be overridden.
Called by the server’s constructor to bind the socket to the desired address. May be overridden.
Must return a Boolean value; if the value is True, the request will be processed, and if it’s False, the request will be denied. This function can be overridden to implement access controls for a server. The default implementation always returns True.
Changed in version 3.6: Support for the context manager protocol was added. Exiting the context manager is equivalent to calling server_close().
This is the superclass of all request handler objects. It defines the interface, given below. A concrete request handler subclass must define a new handle() method, and can override any of the other methods. A new instance of the subclass is created for each request.
Called before the handle() method to perform any initialization actions required. The default implementation does nothing.
This function must do all the work required to service a request. The default implementation does nothing. Several instance attributes are available to it; the request is available as self.request; the client address as self.client_address; and the server instance as self.server, in case it needs access to per-server information.
The type of self.request is different for datagram or stream services. For stream services, self.request is a socket object; for datagram services, self.request is a pair of string and socket.
Called after the handle() method to perform any clean-up actions required. The default implementation does nothing. If setup() raises an exception, this function will not be called.
These BaseRequestHandler subclasses override the setup() and finish() methods, and provide self.rfile and self.wfile attributes. The self.rfile and self.wfile attributes can be read or written, respectively, to get the request data or return data to the client.
The rfile attributes of both classes support the io.BufferedIOBase readable interface, and DatagramRequestHandler.wfile supports the io.BufferedIOBase writable interface.
Changed in version 3.6: StreamRequestHandler.wfile also supports the io.BufferedIOBase writable interface.
This is the server side:
An alternative request handler class that makes use of streams (file-like objects that simplify communication by providing the standard file interface):
The difference is that the readline() call in the second handler will call recv() multiple times until it encounters a newline character, while the single recv() call in the first handler will just return what has been sent from the client in one sendall() call.
This is the client side:
The output of the example should look something like this:
Server:
Client:
This is the server side:
This is the client side:
The output of the example should look exactly like for the TCP server example.
To build asynchronous handlers, use the ThreadingMixIn and ForkingMixIn classes.
An example for the ThreadingMixIn class:
The output of the example should look something like this:
The ForkingMixIn class is used in the same way, except that the server will spawn a new process for each request. Available only on POSIX platforms that support fork().


This is the superclass of all request handler objects. It defines the interface, given below. A concrete request handler subclass must define a new handle() method, and can override any of the other methods. A new instance of the subclass is created for each request.
Called before the handle() method to perform any initialization actions required. The default implementation does nothing.
This function must do all the work required to service a request. The default implementation does nothing. Several instance attributes are available to it; the request is available as self.request; the client address as self.client_address; and the server instance as self.server, in case it needs access to per-server information.
The type of self.request is different for datagram or stream services. For stream services, self.request is a socket object; for datagram services, self.request is a pair of string and socket.
Called after the handle() method to perform any clean-up actions required. The default implementation does nothing. If setup() raises an exception, this function will not be called.


Called after the handle() method to perform any clean-up actions required. The default implementation does nothing. If setup() raises an exception, this function will not be called.


This function must do all the work required to service a request. The default implementation does nothing. Several instance attributes are available to it; the request is available as self.request; the client address as self.client_address; and the server instance as self.server, in case it needs access to per-server information.
The type of self.request is different for datagram or stream services. For stream services, self.request is a socket object; for datagram services, self.request is a pair of string and socket.


Called before the handle() method to perform any initialization actions required. The default implementation does nothing.


This is the superclass of all Server objects in the module. It defines the interface, given below, but does not implement most of the methods, which is done in subclasses. The two parameters are stored in the respective server_address and RequestHandlerClass attributes.
Return an integer file descriptor for the socket on which the server is listening. This function is most commonly passed to selectors, to allow monitoring multiple servers in the same process.
Process a single request. This function calls the following methods in order: get_request(), verify_request(), and process_request(). If the user-provided handle() method of the handler class raises an exception, the server’s handle_error() method will be called. If no request is received within timeout seconds, handle_timeout() will be called and handle_request() will return.
Handle requests until an explicit shutdown() request. Poll for shutdown every poll_interval seconds. Ignores the timeout attribute. It also calls service_actions(), which may be used by a subclass or mixin to provide actions specific to a given service. For example, the ForkingMixIn class uses service_actions() to clean up zombie child processes.
Changed in version 3.3: Added service_actions call to the serve_forever method.
This is called in the serve_forever() loop. This method can be overridden by subclasses or mixin classes to perform actions specific to a given service, such as cleanup actions.
New in version 3.3.
Tell the serve_forever() loop to stop and wait until it does. shutdown() must be called while serve_forever() is running in a different thread otherwise it will deadlock.
Clean up the server. May be overridden.
The family of protocols to which the server’s socket belongs. Common examples are socket.AF_INET and socket.AF_UNIX.
The user-provided request handler class; an instance of this class is created for each request.
The address on which the server is listening. The format of addresses varies depending on the protocol family; see the documentation for the socket module for details. For Internet protocols, this is a tuple containing a string giving the address, and an integer port number: ('127.0.0.1', 80), for example.
The socket object on which the server will listen for incoming requests.
The server classes support the following class variables:
Whether the server will allow the reuse of an address. This defaults to False, and can be set in subclasses to change the policy.
The size of the request queue. If it takes a long time to process a single request, any requests that arrive while the server is busy are placed into a queue, up to request_queue_size requests. Once the queue is full, further requests from clients will get a “Connection denied” error. The default value is usually 5, but this can be overridden by subclasses.
The type of socket used by the server; socket.SOCK_STREAM and socket.SOCK_DGRAM are two common values.
Timeout duration, measured in seconds, or None if no timeout is desired. If handle_request() receives no incoming requests within the timeout period, the handle_timeout() method is called.
There are various server methods that can be overridden by subclasses of base server classes like TCPServer; these methods aren’t useful to external users of the server object.
Actually processes the request by instantiating RequestHandlerClass and calling its handle() method.
Must accept a request from the socket, and return a 2-tuple containing the new socket object to be used to communicate with the client, and the client’s address.
This function is called if the handle() method of a RequestHandlerClass instance raises an exception. The default action is to print the traceback to standard error and continue handling further requests.
Changed in version 3.6: Now only called for exceptions derived from the Exception class.
This function is called when the timeout attribute has been set to a value other than None and the timeout period has passed with no requests being received. The default action for forking servers is to collect the status of any child processes that have exited, while in threading servers this method does nothing.
Calls finish_request() to create an instance of the RequestHandlerClass. If desired, this function can create a new process or thread to handle the request; the ForkingMixIn and ThreadingMixIn classes do this.
Called by the server’s constructor to activate the server. The default behavior for a TCP server just invokes listen() on the server’s socket. May be overridden.
Called by the server’s constructor to bind the socket to the desired address. May be overridden.
Must return a Boolean value; if the value is True, the request will be processed, and if it’s False, the request will be denied. This function can be overridden to implement access controls for a server. The default implementation always returns True.
Changed in version 3.6: Support for the context manager protocol was added. Exiting the context manager is equivalent to calling server_close().


The family of protocols to which the server’s socket belongs. Common examples are socket.AF_INET and socket.AF_UNIX.


Whether the server will allow the reuse of an address. This defaults to False, and can be set in subclasses to change the policy.


Return an integer file descriptor for the socket on which the server is listening. This function is most commonly passed to selectors, to allow monitoring multiple servers in the same process.


Actually processes the request by instantiating RequestHandlerClass and calling its handle() method.


Must accept a request from the socket, and return a 2-tuple containing the new socket object to be used to communicate with the client, and the client’s address.


This function is called if the handle() method of a RequestHandlerClass instance raises an exception. The default action is to print the traceback to standard error and continue handling further requests.
Changed in version 3.6: Now only called for exceptions derived from the Exception class.


Process a single request. This function calls the following methods in order: get_request(), verify_request(), and process_request(). If the user-provided handle() method of the handler class raises an exception, the server’s handle_error() method will be called. If no request is received within timeout seconds, handle_timeout() will be called and handle_request() will return.


This function is called when the timeout attribute has been set to a value other than None and the timeout period has passed with no requests being received. The default action for forking servers is to collect the status of any child processes that have exited, while in threading servers this method does nothing.


Calls finish_request() to create an instance of the RequestHandlerClass. If desired, this function can create a new process or thread to handle the request; the ForkingMixIn and ThreadingMixIn classes do this.


The user-provided request handler class; an instance of this class is created for each request.


The size of the request queue. If it takes a long time to process a single request, any requests that arrive while the server is busy are placed into a queue, up to request_queue_size requests. Once the queue is full, further requests from clients will get a “Connection denied” error. The default value is usually 5, but this can be overridden by subclasses.


Called by the server’s constructor to activate the server. The default behavior for a TCP server just invokes listen() on the server’s socket. May be overridden.


The address on which the server is listening. The format of addresses varies depending on the protocol family; see the documentation for the socket module for details. For Internet protocols, this is a tuple containing a string giving the address, and an integer port number: ('127.0.0.1', 80), for example.


Called by the server’s constructor to bind the socket to the desired address. May be overridden.


Handle requests until an explicit shutdown() request. Poll for shutdown every poll_interval seconds. Ignores the timeout attribute. It also calls service_actions(), which may be used by a subclass or mixin to provide actions specific to a given service. For example, the ForkingMixIn class uses service_actions() to clean up zombie child processes.
Changed in version 3.3: Added service_actions call to the serve_forever method.


This is called in the serve_forever() loop. This method can be overridden by subclasses or mixin classes to perform actions specific to a given service, such as cleanup actions.
New in version 3.3.


Tell the serve_forever() loop to stop and wait until it does. shutdown() must be called while serve_forever() is running in a different thread otherwise it will deadlock.


The socket object on which the server will listen for incoming requests.


The type of socket used by the server; socket.SOCK_STREAM and socket.SOCK_DGRAM are two common values.


Timeout duration, measured in seconds, or None if no timeout is desired. If handle_request() receives no incoming requests within the timeout period, the handle_timeout() method is called.


Must return a Boolean value; if the value is True, the request will be processed, and if it’s False, the request will be denied. This function can be overridden to implement access controls for a server. The default implementation always returns True.


These BaseRequestHandler subclasses override the setup() and finish() methods, and provide self.rfile and self.wfile attributes. The self.rfile and self.wfile attributes can be read or written, respectively, to get the request data or return data to the client.
The rfile attributes of both classes support the io.BufferedIOBase readable interface, and DatagramRequestHandler.wfile supports the io.BufferedIOBase writable interface.
Changed in version 3.6: StreamRequestHandler.wfile also supports the io.BufferedIOBase writable interface.


Forking and threading versions of each type of server can be created using these mix-in classes. For instance, ThreadingUDPServer is created as follows:
The mix-in class comes first, since it overrides a method defined in UDPServer. Setting the various attributes also changes the behavior of the underlying server mechanism.
ForkingMixIn and the Forking classes mentioned below are only available on POSIX platforms that support fork().
socketserver.ForkingMixIn.server_close() waits until all child processes complete, except if socketserver.ForkingMixIn.block_on_close attribute is false.
socketserver.ThreadingMixIn.server_close() waits until all non-daemon threads complete, except if socketserver.ThreadingMixIn.block_on_close attribute is false. Use daemonic threads by setting ThreadingMixIn.daemon_threads to True to not wait until threads complete.
Changed in version 3.7: socketserver.ForkingMixIn.server_close() and socketserver.ThreadingMixIn.server_close() now waits until all child processes and non-daemonic threads complete. Add a new socketserver.ForkingMixIn.block_on_close class attribute to opt-in for the pre-3.7 behaviour.


These classes are pre-defined using the mix-in classes.


This uses the Internet TCP protocol, which provides for continuous streams of data between the client and server. If bind_and_activate is true, the constructor automatically attempts to invoke server_bind() and server_activate(). The other parameters are passed to the BaseServer base class.


This uses datagrams, which are discrete packets of information that may arrive out of order or be lost while in transit. The parameters are the same as for TCPServer.


These more infrequently used classes are similar to the TCP and UDP classes, but use Unix domain sockets; they’re not available on non-Unix platforms. The parameters are the same as for TCPServer.


Return a new sorted list from the items in iterable.
Has two optional arguments which must be specified as keyword arguments.
key specifies a function of one argument that is used to extract a comparison key from each element in iterable (for example, key=str.lower). The default value is None (compare the elements directly).
reverse is a boolean value. If set to True, then the list elements are sorted as if each comparison were reversed.
Use functools.cmp_to_key() to convert an old-style cmp function to a key function.
The built-in sorted() function is guaranteed to be stable. A sort is stable if it guarantees not to change the relative order of elements that compare equal — this is helpful for sorting in multiple passes (for example, sort by department, then by salary grade).
For sorting examples and a brief sorting tutorial, see Sorting HOW TO.


This module provides access to the Unix shadow password database. It is available on various Unix versions.
You must have enough privileges to access the shadow password database (this usually means you have to be root).
Shadow password database entries are reported as a tuple-like object, whose attributes correspond to the members of the spwd structure (Attribute field below, see <shadow.h>):
Index
Attribute
Meaning
0
sp_namp
Login name
1
sp_pwdp
Encrypted password
2
sp_lstchg
Date of last change
3
sp_min
Minimal number of days between changes
4
sp_max
Maximum number of days between changes
5
sp_warn
Number of days before password expires to warn user about it
6
sp_inact
Number of days after password expires until account is disabled
7
sp_expire
Number of days since 1970-01-01 when account expires
8
sp_flag
Reserved
The sp_namp and sp_pwdp items are strings, all others are integers. KeyError is raised if the entry asked for cannot be found.
The following functions are defined:
Return the shadow password database entry for the given user name.
Changed in version 3.6: Raises a PermissionError instead of KeyError if the user doesn’t have privileges.
Return a list of all available shadow password database entries, in arbitrary order.
See also
An interface to the group database, similar to this.
An interface to the normal password database, similar to this.


Return a list of all available shadow password database entries, in arbitrary order.


Return the shadow password database entry for the given user name.
Changed in version 3.6: Raises a PermissionError instead of KeyError if the user doesn’t have privileges.


Source code: Lib/sqlite3/
SQLite is a C library that provides a lightweight disk-based database that doesn’t require a separate server process and allows accessing the database using a nonstandard variant of the SQL query language. Some applications can use SQLite for internal data storage. It’s also possible to prototype an application using SQLite and then port the code to a larger database such as PostgreSQL or Oracle.
The sqlite3 module was written by Gerhard Häring. It provides a SQL interface compliant with the DB-API 2.0 specification described by PEP 249.
To use the module, you must first create a Connection object that represents the database. Here the data will be stored in the example.db file:
You can also supply the special name :memory: to create a database in RAM.
Once you have a Connection, you can create a Cursor object and call its execute() method to perform SQL commands:
The data you’ve saved is persistent and is available in subsequent sessions:
To retrieve data after executing a SELECT statement, you can either treat the cursor as an iterator, call the cursor’s fetchone() method to retrieve a single matching row, or call fetchall() to get a list of the matching rows.
This example uses the iterator form:
Usually your SQL operations will need to use values from Python variables. You shouldn’t assemble your query using Python’s string operations because doing so is insecure; it makes your program vulnerable to an SQL injection attack (see the xkcd webcomic for a humorous example of what can go wrong):
Instead, use the DB-API’s parameter substitution. Put a placeholder wherever you want to use a value, and then provide a tuple of values as the second argument to the cursor’s execute() method. An SQL statement may use one of two kinds of placeholders: question marks (qmark style) or named placeholders (named style). For the qmark style, parameters must be a sequence. For the named style, it can be either a sequence or dict instance. The length of the sequence must match the number of placeholders, or a ProgrammingError is raised. If a dict is given, it must contain keys for all named parameters. Any extra items are ignored. Here’s an example of both styles:
See also
The SQLite web page; the documentation describes the syntax and the available data types for the supported SQL dialect.
Tutorial, reference and examples for learning SQL syntax.
PEP written by Marc-André Lemburg.
The version number of this module, as a string. This is not the version of the SQLite library.
The version number of this module, as a tuple of integers. This is not the version of the SQLite library.
The version number of the run-time SQLite library, as a string.
The version number of the run-time SQLite library, as a tuple of integers.
This constant is meant to be used with the detect_types parameter of the connect() function.
Setting it makes the sqlite3 module parse the declared type for each column it returns. It will parse out the first word of the declared type, i. e. for “integer primary key”, it will parse out “integer”, or for “number(10)” it will parse out “number”. Then for that column, it will look into the converters dictionary and use the converter function registered for that type there.
This constant is meant to be used with the detect_types parameter of the connect() function.
Setting this makes the SQLite interface parse the column name for each column it returns. It will look for a string formed [mytype] in there, and then decide that ‘mytype’ is the type of the column. It will try to find an entry of ‘mytype’ in the converters dictionary and then use the converter function found there to return the value. The column name found in Cursor.description does not include the type, i. e. if you use something like 'as "Expiration date [datetime]"' in your SQL, then we will parse out everything until the first '[' for the column name and strip the preceeding space: the column name would simply be “Expiration date”.
Opens a connection to the SQLite database file database. By default returns a Connection object, unless a custom factory is given.
database is a path-like object giving the pathname (absolute or relative to the current working directory) of the database file to be opened. You can use ":memory:" to open a database connection to a database that resides in RAM instead of on disk.
When a database is accessed by multiple connections, and one of the processes modifies the database, the SQLite database is locked until that transaction is committed. The timeout parameter specifies how long the connection should wait for the lock to go away until raising an exception. The default for the timeout parameter is 5.0 (five seconds).
For the isolation_level parameter, please see the isolation_level property of Connection objects.
SQLite natively supports only the types TEXT, INTEGER, REAL, BLOB and NULL. If you want to use other types you must add support for them yourself. The detect_types parameter and the using custom converters registered with the module-level register_converter() function allow you to easily do that.
detect_types defaults to 0 (i. e. off, no type detection), you can set it to any combination of PARSE_DECLTYPES and PARSE_COLNAMES to turn type detection on. Due to SQLite behaviour, types can’t be detected for generated fields (for example max(data)), even when detect_types parameter is set. In such case, the returned type is str.
By default, check_same_thread is True and only the creating thread may use the connection. If set False, the returned connection may be shared across multiple threads. When using multiple threads with the same connection writing operations should be serialized by the user to avoid data corruption.
By default, the sqlite3 module uses its Connection class for the connect call. You can, however, subclass the Connection class and make connect() use your class instead by providing your class for the factory parameter.
Consult the section SQLite and Python types of this manual for details.
The sqlite3 module internally uses a statement cache to avoid SQL parsing overhead. If you want to explicitly set the number of statements that are cached for the connection, you can set the cached_statements parameter. The currently implemented default is to cache 100 statements.
If uri is true, database is interpreted as a URI. This allows you to specify options. For example, to open a database in read-only mode you can use:
More information about this feature, including a list of recognized options, can be found in the SQLite URI documentation.
Raises an auditing event sqlite3.connect with argument database.
Changed in version 3.4: Added the uri parameter.
Changed in version 3.7: database can now also be a path-like object, not only a string.
Registers a callable to convert a bytestring from the database into a custom Python type. The callable will be invoked for all database values that are of the type typename. Confer the parameter detect_types of the connect() function for how the type detection works. Note that typename and the name of the type in your query are matched in case-insensitive manner.
Registers a callable to convert the custom Python type type into one of SQLite’s supported types. The callable callable accepts as single parameter the Python value, and must return a value of the following types: int, float, str or bytes.
Returns True if the string sql contains one or more complete SQL statements terminated by semicolons. It does not verify that the SQL is syntactically correct, only that there are no unclosed string literals and the statement is terminated by a semicolon.
This can be used to build a shell for SQLite, as in the following example:
By default you will not get any tracebacks in user-defined functions, aggregates, converters, authorizer callbacks etc. If you want to debug them, you can call this function with flag set to True. Afterwards, you will get tracebacks from callbacks on sys.stderr. Use False to disable the feature again.
A SQLite database connection has the following attributes and methods:
Get or set the current default isolation level. None for autocommit mode or one of “DEFERRED”, “IMMEDIATE” or “EXCLUSIVE”. See section Controlling Transactions for a more detailed explanation.
True if a transaction is active (there are uncommitted changes), False otherwise. Read-only attribute.
New in version 3.2.
The cursor method accepts a single optional parameter factory. If supplied, this must be a callable returning an instance of Cursor or its subclasses.
This method commits the current transaction. If you don’t call this method, anything you did since the last call to commit() is not visible from other database connections. If you wonder why you don’t see the data you’ve written to the database, please check you didn’t forget to call this method.
This method rolls back any changes to the database since the last call to commit().
This closes the database connection. Note that this does not automatically call commit(). If you just close your database connection without calling commit() first, your changes will be lost!
This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s execute() method with the parameters given, and returns the cursor.
This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s executemany() method with the parameters given, and returns the cursor.
This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s executescript() method with the given sql_script, and returns the cursor.
Creates a user-defined function that you can later use from within SQL statements under the function name name. num_params is the number of parameters the function accepts (if num_params is -1, the function may take any number of arguments), and func is a Python callable that is called as the SQL function. If deterministic is true, the created function is marked as deterministic, which allows SQLite to perform additional optimizations. This flag is supported by SQLite 3.8.3 or higher, NotSupportedError will be raised if used with older versions.
The function can return any of the types supported by SQLite: bytes, str, int, float and None.
Changed in version 3.8: The deterministic parameter was added.
Example:
Creates a user-defined aggregate function.
The aggregate class must implement a step method, which accepts the number of parameters num_params (if num_params is -1, the function may take any number of arguments), and a finalize method which will return the final result of the aggregate.
The finalize method can return any of the types supported by SQLite: bytes, str, int, float and None.
Example:
Creates a collation with the specified name and callable. The callable will be passed two string arguments. It should return -1 if the first is ordered lower than the second, 0 if they are ordered equal and 1 if the first is ordered higher than the second. Note that this controls sorting (ORDER BY in SQL) so your comparisons don’t affect other SQL operations.
Note that the callable will get its parameters as Python bytestrings, which will normally be encoded in UTF-8.
The following example shows a custom collation that sorts “the wrong way”:
To remove a collation, call create_collation with None as callable:
You can call this method from a different thread to abort any queries that might be executing on the connection. The query will then abort and the caller will get an exception.
This routine registers a callback. The callback is invoked for each attempt to access a column of a table in the database. The callback should return SQLITE_OK if access is allowed, SQLITE_DENY if the entire SQL statement should be aborted with an error and SQLITE_IGNORE if the column should be treated as a NULL value. These constants are available in the sqlite3 module.
The first argument to the callback signifies what kind of operation is to be authorized. The second and third argument will be arguments or None depending on the first argument. The 4th argument is the name of the database (“main”, “temp”, etc.) if applicable. The 5th argument is the name of the inner-most trigger or view that is responsible for the access attempt or None if this access attempt is directly from input SQL code.
Please consult the SQLite documentation about the possible values for the first argument and the meaning of the second and third argument depending on the first one. All necessary constants are available in the sqlite3 module.
This routine registers a callback. The callback is invoked for every n instructions of the SQLite virtual machine. This is useful if you want to get called from SQLite during long-running operations, for example to update a GUI.
If you want to clear any previously installed progress handler, call the method with None for handler.
Returning a non-zero value from the handler function will terminate the currently executing query and cause it to raise an OperationalError exception.
Registers trace_callback to be called for each SQL statement that is actually executed by the SQLite backend.
The only argument passed to the callback is the statement (as string) that is being executed. The return value of the callback is ignored. Note that the backend does not only run statements passed to the Cursor.execute() methods. Other sources include the transaction management of the Python module and the execution of triggers defined in the current database.
Passing None as trace_callback will disable the trace callback.
New in version 3.3.
This routine allows/disallows the SQLite engine to load SQLite extensions from shared libraries. SQLite extensions can define new functions, aggregates or whole new virtual table implementations. One well-known extension is the fulltext-search extension distributed with SQLite.
Loadable extensions are disabled by default. See 1.
New in version 3.2.
This routine loads a SQLite extension from a shared library. You have to enable extension loading with enable_load_extension() before you can use this routine.
Loadable extensions are disabled by default. See 1.
New in version 3.2.
You can change this attribute to a callable that accepts the cursor and the original row as a tuple and will return the real result row. This way, you can implement more advanced ways of returning results, such as returning an object that can also access columns by name.
Example:
If returning a tuple doesn’t suffice and you want name-based access to columns, you should consider setting row_factory to the highly-optimized sqlite3.Row type. Row provides both index-based and case-insensitive name-based access to columns with almost no memory overhead. It will probably be better than your own custom dictionary-based approach or even a db_row based solution.
Using this attribute you can control what objects are returned for the TEXT data type. By default, this attribute is set to str and the sqlite3 module will return Unicode objects for TEXT. If you want to return bytestrings instead, you can set it to bytes.
You can also set it to any other callable that accepts a single bytestring parameter and returns the resulting object.
See the following example code for illustration:
Returns the total number of database rows that have been modified, inserted, or deleted since the database connection was opened.
Returns an iterator to dump the database in an SQL text format. Useful when saving an in-memory database for later restoration. This function provides the same capabilities as the .dump command in the sqlite3 shell.
Example:
This method makes a backup of a SQLite database even while it’s being accessed by other clients, or concurrently by the same connection. The copy will be written into the mandatory argument target, that must be another Connection instance.
By default, or when pages is either 0 or a negative integer, the entire database is copied in a single step; otherwise the method performs a loop copying up to pages pages at a time.
If progress is specified, it must either be None or a callable object that will be executed at each iteration with three integer arguments, respectively the status of the last iteration, the remaining number of pages still to be copied and the total number of pages.
The name argument specifies the database name that will be copied: it must be a string containing either "main", the default, to indicate the main database, "temp" to indicate the temporary database or the name specified after the AS keyword in an ATTACH DATABASE statement for an attached database.
The sleep argument specifies the number of seconds to sleep by between successive attempts to backup remaining pages, can be specified either as an integer or a floating point value.
Example 1, copy an existing database into another:
Example 2, copy an existing database into a transient copy:
Availability: SQLite 3.6.11 or higher
New in version 3.7.
A Cursor instance has the following attributes and methods.
Executes an SQL statement. Values may be bound to the statement using placeholders.
execute() will only execute a single SQL statement. If you try to execute more than one statement with it, it will raise a Warning. Use executescript() if you want to execute multiple SQL statements with one call.
Executes a parameterized SQL command against all parameter sequences or mappings found in the sequence seq_of_parameters. The sqlite3 module also allows using an iterator yielding parameters instead of a sequence.
Here’s a shorter example using a generator:
This is a nonstandard convenience method for executing multiple SQL statements at once. It issues a COMMIT statement first, then executes the SQL script it gets as a parameter.
sql_script can be an instance of str.
Example:
Fetches the next row of a query result set, returning a single sequence, or None when no more data is available.
Fetches the next set of rows of a query result, returning a list. An empty list is returned when no more rows are available.
The number of rows to fetch per call is specified by the size parameter. If it is not given, the cursor’s arraysize determines the number of rows to be fetched. The method should try to fetch as many rows as indicated by the size parameter. If this is not possible due to the specified number of rows not being available, fewer rows may be returned.
Note there are performance considerations involved with the size parameter. For optimal performance, it is usually best to use the arraysize attribute. If the size parameter is used, then it is best for it to retain the same value from one fetchmany() call to the next.
Fetches all (remaining) rows of a query result, returning a list. Note that the cursor’s arraysize attribute can affect the performance of this operation. An empty list is returned when no rows are available.
Close the cursor now (rather than whenever __del__ is called).
The cursor will be unusable from this point forward; a ProgrammingError exception will be raised if any operation is attempted with the cursor.
Although the Cursor class of the sqlite3 module implements this attribute, the database engine’s own support for the determination of “rows affected”/”rows selected” is quirky.
For executemany() statements, the number of modifications are summed up into rowcount.
As required by the Python DB API Spec, the rowcount attribute “is -1 in case no executeXX() has been performed on the cursor or the rowcount of the last operation is not determinable by the interface”. This includes SELECT statements because we cannot determine the number of rows a query produced until all rows were fetched.
With SQLite versions before 3.6.5, rowcount is set to 0 if you make a DELETE FROM table without any condition.
This read-only attribute provides the rowid of the last modified row. It is only set if you issued an INSERT or a REPLACE statement using the execute() method. For operations other than INSERT or REPLACE or when executemany() is called, lastrowid is set to None.
If the INSERT or REPLACE statement failed to insert the previous successful rowid is returned.
Changed in version 3.6: Added support for the REPLACE statement.
Read/write attribute that controls the number of rows returned by fetchmany(). The default value is 1 which means a single row would be fetched per call.
This read-only attribute provides the column names of the last query. To remain compatible with the Python DB API, it returns a 7-tuple for each column where the last six items of each tuple are None.
It is set for SELECT statements without any matching rows as well.
This read-only attribute provides the SQLite database Connection used by the Cursor object. A Cursor object created by calling con.cursor() will have a connection attribute that refers to con:
A Row instance serves as a highly optimized row_factory for Connection objects. It tries to mimic a tuple in most of its features.
It supports mapping access by column name and index, iteration, representation, equality testing and len().
If two Row objects have exactly the same columns and their members are equal, they compare equal.
This method returns a list of column names. Immediately after a query, it is the first member of each tuple in Cursor.description.
Changed in version 3.5: Added support of slicing.
Let’s assume we initialize a table as in the example given above:
Now we plug Row in:
A subclass of Exception.
The base class of the other exceptions in this module. It is a subclass of Exception.
Exception raised for errors that are related to the database.
Exception raised when the relational integrity of the database is affected, e.g. a foreign key check fails. It is a subclass of DatabaseError.
Exception raised for programming errors, e.g. table not found or already exists, syntax error in the SQL statement, wrong number of parameters specified, etc. It is a subclass of DatabaseError.
Exception raised for errors that are related to the database’s operation and not necessarily under the control of the programmer, e.g. an unexpected disconnect occurs, the data source name is not found, a transaction could not be processed, etc. It is a subclass of DatabaseError.
Exception raised in case a method or database API was used which is not supported by the database, e.g. calling the rollback() method on a connection that does not support transaction or has transactions turned off. It is a subclass of DatabaseError.
SQLite natively supports the following types: NULL, INTEGER, REAL, TEXT, BLOB.
The following Python types can thus be sent to SQLite without any problem:
Python type
SQLite type
None
NULL
int
INTEGER
float
REAL
str
TEXT
bytes
BLOB
This is how SQLite types are converted to Python types by default:
SQLite type
Python type
NULL
None
INTEGER
int
REAL
float
TEXT
depends on text_factory, str by default
BLOB
bytes
The type system of the sqlite3 module is extensible in two ways: you can store additional Python types in a SQLite database via object adaptation, and you can let the sqlite3 module convert SQLite types to different Python types via converters.
As described before, SQLite supports only a limited set of types natively. To use other Python types with SQLite, you must adapt them to one of the sqlite3 module’s supported types for SQLite: one of NoneType, int, float, str, bytes.
There are two ways to enable the sqlite3 module to adapt a custom Python type to one of the supported ones.
This is a good approach if you write the class yourself. Let’s suppose you have a class like this:
Now you want to store the point in a single SQLite column. First you’ll have to choose one of the supported types to be used for representing the point. Let’s just use str and separate the coordinates using a semicolon. Then you need to give your class a method __conform__(self, protocol) which must return the converted value. The parameter protocol will be PrepareProtocol.
The other possibility is to create a function that converts the type to the string representation and register the function with register_adapter().
The sqlite3 module has two default adapters for Python’s built-in datetime.date and datetime.datetime types. Now let’s suppose we want to store datetime.datetime objects not in ISO representation, but as a Unix timestamp.
Writing an adapter lets you send custom Python types to SQLite. But to make it really useful we need to make the Python to SQLite to Python roundtrip work.
Enter converters.
Let’s go back to the Point class. We stored the x and y coordinates separated via semicolons as strings in SQLite.
First, we’ll define a converter function that accepts the string as a parameter and constructs a Point object from it.
Note
Converter functions always get called with a bytes object, no matter under which data type you sent the value to SQLite.
Now you need to make the sqlite3 module know that what you select from the database is actually a point. There are two ways of doing this:
Both ways are described in section Module functions and constants, in the entries for the constants PARSE_DECLTYPES and PARSE_COLNAMES.
The following example illustrates both approaches.
There are default adapters for the date and datetime types in the datetime module. They will be sent as ISO dates/ISO timestamps to SQLite.
The default converters are registered under the name “date” for datetime.date and under the name “timestamp” for datetime.datetime.
This way, you can use date/timestamps from Python without any additional fiddling in most cases. The format of the adapters is also compatible with the experimental SQLite date/time functions.
The following example demonstrates this.
If a timestamp stored in SQLite has a fractional part longer than 6 numbers, its value will be truncated to microsecond precision by the timestamp converter.
The underlying sqlite3 library operates in autocommit mode by default, but the Python sqlite3 module by default does not.
autocommit mode means that statements that modify the database take effect immediately. A BEGIN or SAVEPOINT statement disables autocommit mode, and a COMMIT, a ROLLBACK, or a RELEASE that ends the outermost transaction, turns autocommit mode back on.
The Python sqlite3 module by default issues a BEGIN statement implicitly before a Data Modification Language (DML) statement (i.e. INSERT/UPDATE/DELETE/REPLACE).
You can control which kind of BEGIN statements sqlite3 implicitly executes via the isolation_level parameter to the connect() call, or via the isolation_level property of connections. If you specify no isolation_level, a plain BEGIN is used, which is equivalent to specifying DEFERRED. Other possible values are IMMEDIATE and EXCLUSIVE.
You can disable the sqlite3 module’s implicit transaction management by setting isolation_level to None. This will leave the underlying sqlite3 library operating in autocommit mode. You can then completely control the transaction state by explicitly issuing BEGIN, ROLLBACK, SAVEPOINT, and RELEASE statements in your code.
Changed in version 3.6: sqlite3 used to implicitly commit an open transaction before DDL statements. This is no longer the case.
Using the nonstandard execute(), executemany() and executescript() methods of the Connection object, your code can be written more concisely because you don’t have to create the (often superfluous) Cursor objects explicitly. Instead, the Cursor objects are created implicitly and these shortcut methods return the cursor objects. This way, you can execute a SELECT statement and iterate over it directly using only a single call on the Connection object.
One useful feature of the sqlite3 module is the built-in sqlite3.Row class designed to be used as a row factory.
Rows wrapped with this class can be accessed both by index (like tuples) and case-insensitively by name:
Connection objects can be used as context managers that automatically commit or rollback transactions. In the event of an exception, the transaction is rolled back; otherwise, the transaction is committed:
The sqlite3 module is not built with loadable extension support by default, because some platforms (notably Mac OS X) have SQLite libraries which are compiled without this feature. To get loadable extension support, you must pass --enable-loadable-sqlite-extensions to configure.


Returns True if the string sql contains one or more complete SQL statements terminated by semicolons. It does not verify that the SQL is syntactically correct, only that there are no unclosed string literals and the statement is terminated by a semicolon.
This can be used to build a shell for SQLite, as in the following example:


Opens a connection to the SQLite database file database. By default returns a Connection object, unless a custom factory is given.
database is a path-like object giving the pathname (absolute or relative to the current working directory) of the database file to be opened. You can use ":memory:" to open a database connection to a database that resides in RAM instead of on disk.
When a database is accessed by multiple connections, and one of the processes modifies the database, the SQLite database is locked until that transaction is committed. The timeout parameter specifies how long the connection should wait for the lock to go away until raising an exception. The default for the timeout parameter is 5.0 (five seconds).
For the isolation_level parameter, please see the isolation_level property of Connection objects.
SQLite natively supports only the types TEXT, INTEGER, REAL, BLOB and NULL. If you want to use other types you must add support for them yourself. The detect_types parameter and the using custom converters registered with the module-level register_converter() function allow you to easily do that.
detect_types defaults to 0 (i. e. off, no type detection), you can set it to any combination of PARSE_DECLTYPES and PARSE_COLNAMES to turn type detection on. Due to SQLite behaviour, types can’t be detected for generated fields (for example max(data)), even when detect_types parameter is set. In such case, the returned type is str.
By default, check_same_thread is True and only the creating thread may use the connection. If set False, the returned connection may be shared across multiple threads. When using multiple threads with the same connection writing operations should be serialized by the user to avoid data corruption.
By default, the sqlite3 module uses its Connection class for the connect call. You can, however, subclass the Connection class and make connect() use your class instead by providing your class for the factory parameter.
Consult the section SQLite and Python types of this manual for details.
The sqlite3 module internally uses a statement cache to avoid SQL parsing overhead. If you want to explicitly set the number of statements that are cached for the connection, you can set the cached_statements parameter. The currently implemented default is to cache 100 statements.
If uri is true, database is interpreted as a URI. This allows you to specify options. For example, to open a database in read-only mode you can use:
More information about this feature, including a list of recognized options, can be found in the SQLite URI documentation.
Raises an auditing event sqlite3.connect with argument database.
Changed in version 3.4: Added the uri parameter.
Changed in version 3.7: database can now also be a path-like object, not only a string.


A SQLite database connection has the following attributes and methods:
Get or set the current default isolation level. None for autocommit mode or one of “DEFERRED”, “IMMEDIATE” or “EXCLUSIVE”. See section Controlling Transactions for a more detailed explanation.
True if a transaction is active (there are uncommitted changes), False otherwise. Read-only attribute.
New in version 3.2.
The cursor method accepts a single optional parameter factory. If supplied, this must be a callable returning an instance of Cursor or its subclasses.
This method commits the current transaction. If you don’t call this method, anything you did since the last call to commit() is not visible from other database connections. If you wonder why you don’t see the data you’ve written to the database, please check you didn’t forget to call this method.
This method rolls back any changes to the database since the last call to commit().
This closes the database connection. Note that this does not automatically call commit(). If you just close your database connection without calling commit() first, your changes will be lost!
This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s execute() method with the parameters given, and returns the cursor.
This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s executemany() method with the parameters given, and returns the cursor.
This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s executescript() method with the given sql_script, and returns the cursor.
Creates a user-defined function that you can later use from within SQL statements under the function name name. num_params is the number of parameters the function accepts (if num_params is -1, the function may take any number of arguments), and func is a Python callable that is called as the SQL function. If deterministic is true, the created function is marked as deterministic, which allows SQLite to perform additional optimizations. This flag is supported by SQLite 3.8.3 or higher, NotSupportedError will be raised if used with older versions.
The function can return any of the types supported by SQLite: bytes, str, int, float and None.
Changed in version 3.8: The deterministic parameter was added.
Example:
Creates a user-defined aggregate function.
The aggregate class must implement a step method, which accepts the number of parameters num_params (if num_params is -1, the function may take any number of arguments), and a finalize method which will return the final result of the aggregate.
The finalize method can return any of the types supported by SQLite: bytes, str, int, float and None.
Example:
Creates a collation with the specified name and callable. The callable will be passed two string arguments. It should return -1 if the first is ordered lower than the second, 0 if they are ordered equal and 1 if the first is ordered higher than the second. Note that this controls sorting (ORDER BY in SQL) so your comparisons don’t affect other SQL operations.
Note that the callable will get its parameters as Python bytestrings, which will normally be encoded in UTF-8.
The following example shows a custom collation that sorts “the wrong way”:
To remove a collation, call create_collation with None as callable:
You can call this method from a different thread to abort any queries that might be executing on the connection. The query will then abort and the caller will get an exception.
This routine registers a callback. The callback is invoked for each attempt to access a column of a table in the database. The callback should return SQLITE_OK if access is allowed, SQLITE_DENY if the entire SQL statement should be aborted with an error and SQLITE_IGNORE if the column should be treated as a NULL value. These constants are available in the sqlite3 module.
The first argument to the callback signifies what kind of operation is to be authorized. The second and third argument will be arguments or None depending on the first argument. The 4th argument is the name of the database (“main”, “temp”, etc.) if applicable. The 5th argument is the name of the inner-most trigger or view that is responsible for the access attempt or None if this access attempt is directly from input SQL code.
Please consult the SQLite documentation about the possible values for the first argument and the meaning of the second and third argument depending on the first one. All necessary constants are available in the sqlite3 module.
This routine registers a callback. The callback is invoked for every n instructions of the SQLite virtual machine. This is useful if you want to get called from SQLite during long-running operations, for example to update a GUI.
If you want to clear any previously installed progress handler, call the method with None for handler.
Returning a non-zero value from the handler function will terminate the currently executing query and cause it to raise an OperationalError exception.
Registers trace_callback to be called for each SQL statement that is actually executed by the SQLite backend.
The only argument passed to the callback is the statement (as string) that is being executed. The return value of the callback is ignored. Note that the backend does not only run statements passed to the Cursor.execute() methods. Other sources include the transaction management of the Python module and the execution of triggers defined in the current database.
Passing None as trace_callback will disable the trace callback.
New in version 3.3.
This routine allows/disallows the SQLite engine to load SQLite extensions from shared libraries. SQLite extensions can define new functions, aggregates or whole new virtual table implementations. One well-known extension is the fulltext-search extension distributed with SQLite.
Loadable extensions are disabled by default. See 1.
New in version 3.2.
This routine loads a SQLite extension from a shared library. You have to enable extension loading with enable_load_extension() before you can use this routine.
Loadable extensions are disabled by default. See 1.
New in version 3.2.
You can change this attribute to a callable that accepts the cursor and the original row as a tuple and will return the real result row. This way, you can implement more advanced ways of returning results, such as returning an object that can also access columns by name.
Example:
If returning a tuple doesn’t suffice and you want name-based access to columns, you should consider setting row_factory to the highly-optimized sqlite3.Row type. Row provides both index-based and case-insensitive name-based access to columns with almost no memory overhead. It will probably be better than your own custom dictionary-based approach or even a db_row based solution.
Using this attribute you can control what objects are returned for the TEXT data type. By default, this attribute is set to str and the sqlite3 module will return Unicode objects for TEXT. If you want to return bytestrings instead, you can set it to bytes.
You can also set it to any other callable that accepts a single bytestring parameter and returns the resulting object.
See the following example code for illustration:
Returns the total number of database rows that have been modified, inserted, or deleted since the database connection was opened.
Returns an iterator to dump the database in an SQL text format. Useful when saving an in-memory database for later restoration. This function provides the same capabilities as the .dump command in the sqlite3 shell.
Example:
This method makes a backup of a SQLite database even while it’s being accessed by other clients, or concurrently by the same connection. The copy will be written into the mandatory argument target, that must be another Connection instance.
By default, or when pages is either 0 or a negative integer, the entire database is copied in a single step; otherwise the method performs a loop copying up to pages pages at a time.
If progress is specified, it must either be None or a callable object that will be executed at each iteration with three integer arguments, respectively the status of the last iteration, the remaining number of pages still to be copied and the total number of pages.
The name argument specifies the database name that will be copied: it must be a string containing either "main", the default, to indicate the main database, "temp" to indicate the temporary database or the name specified after the AS keyword in an ATTACH DATABASE statement for an attached database.
The sleep argument specifies the number of seconds to sleep by between successive attempts to backup remaining pages, can be specified either as an integer or a floating point value.
Example 1, copy an existing database into another:
Example 2, copy an existing database into a transient copy:
Availability: SQLite 3.6.11 or higher
New in version 3.7.


This method makes a backup of a SQLite database even while it’s being accessed by other clients, or concurrently by the same connection. The copy will be written into the mandatory argument target, that must be another Connection instance.
By default, or when pages is either 0 or a negative integer, the entire database is copied in a single step; otherwise the method performs a loop copying up to pages pages at a time.
If progress is specified, it must either be None or a callable object that will be executed at each iteration with three integer arguments, respectively the status of the last iteration, the remaining number of pages still to be copied and the total number of pages.
The name argument specifies the database name that will be copied: it must be a string containing either "main", the default, to indicate the main database, "temp" to indicate the temporary database or the name specified after the AS keyword in an ATTACH DATABASE statement for an attached database.
The sleep argument specifies the number of seconds to sleep by between successive attempts to backup remaining pages, can be specified either as an integer or a floating point value.
Example 1, copy an existing database into another:
Example 2, copy an existing database into a transient copy:
Availability: SQLite 3.6.11 or higher
New in version 3.7.


This closes the database connection. Note that this does not automatically call commit(). If you just close your database connection without calling commit() first, your changes will be lost!


This method commits the current transaction. If you don’t call this method, anything you did since the last call to commit() is not visible from other database connections. If you wonder why you don’t see the data you’ve written to the database, please check you didn’t forget to call this method.


Creates a user-defined aggregate function.
The aggregate class must implement a step method, which accepts the number of parameters num_params (if num_params is -1, the function may take any number of arguments), and a finalize method which will return the final result of the aggregate.
The finalize method can return any of the types supported by SQLite: bytes, str, int, float and None.
Example:


Creates a collation with the specified name and callable. The callable will be passed two string arguments. It should return -1 if the first is ordered lower than the second, 0 if they are ordered equal and 1 if the first is ordered higher than the second. Note that this controls sorting (ORDER BY in SQL) so your comparisons don’t affect other SQL operations.
Note that the callable will get its parameters as Python bytestrings, which will normally be encoded in UTF-8.
The following example shows a custom collation that sorts “the wrong way”:
To remove a collation, call create_collation with None as callable:


Creates a user-defined function that you can later use from within SQL statements under the function name name. num_params is the number of parameters the function accepts (if num_params is -1, the function may take any number of arguments), and func is a Python callable that is called as the SQL function. If deterministic is true, the created function is marked as deterministic, which allows SQLite to perform additional optimizations. This flag is supported by SQLite 3.8.3 or higher, NotSupportedError will be raised if used with older versions.
The function can return any of the types supported by SQLite: bytes, str, int, float and None.
Changed in version 3.8: The deterministic parameter was added.
Example:


The cursor method accepts a single optional parameter factory. If supplied, this must be a callable returning an instance of Cursor or its subclasses.


This routine allows/disallows the SQLite engine to load SQLite extensions from shared libraries. SQLite extensions can define new functions, aggregates or whole new virtual table implementations. One well-known extension is the fulltext-search extension distributed with SQLite.
Loadable extensions are disabled by default. See 1.
New in version 3.2.


This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s execute() method with the parameters given, and returns the cursor.


This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s executemany() method with the parameters given, and returns the cursor.


This is a nonstandard shortcut that creates a cursor object by calling the cursor() method, calls the cursor’s executescript() method with the given sql_script, and returns the cursor.


You can call this method from a different thread to abort any queries that might be executing on the connection. The query will then abort and the caller will get an exception.


True if a transaction is active (there are uncommitted changes), False otherwise. Read-only attribute.
New in version 3.2.


Get or set the current default isolation level. None for autocommit mode or one of “DEFERRED”, “IMMEDIATE” or “EXCLUSIVE”. See section Controlling Transactions for a more detailed explanation.


Returns an iterator to dump the database in an SQL text format. Useful when saving an in-memory database for later restoration. This function provides the same capabilities as the .dump command in the sqlite3 shell.
Example:


This routine loads a SQLite extension from a shared library. You have to enable extension loading with enable_load_extension() before you can use this routine.
Loadable extensions are disabled by default. See 1.
New in version 3.2.


This method rolls back any changes to the database since the last call to commit().


You can change this attribute to a callable that accepts the cursor and the original row as a tuple and will return the real result row. This way, you can implement more advanced ways of returning results, such as returning an object that can also access columns by name.
Example:
If returning a tuple doesn’t suffice and you want name-based access to columns, you should consider setting row_factory to the highly-optimized sqlite3.Row type. Row provides both index-based and case-insensitive name-based access to columns with almost no memory overhead. It will probably be better than your own custom dictionary-based approach or even a db_row based solution.


This routine registers a callback. The callback is invoked for each attempt to access a column of a table in the database. The callback should return SQLITE_OK if access is allowed, SQLITE_DENY if the entire SQL statement should be aborted with an error and SQLITE_IGNORE if the column should be treated as a NULL value. These constants are available in the sqlite3 module.
The first argument to the callback signifies what kind of operation is to be authorized. The second and third argument will be arguments or None depending on the first argument. The 4th argument is the name of the database (“main”, “temp”, etc.) if applicable. The 5th argument is the name of the inner-most trigger or view that is responsible for the access attempt or None if this access attempt is directly from input SQL code.
Please consult the SQLite documentation about the possible values for the first argument and the meaning of the second and third argument depending on the first one. All necessary constants are available in the sqlite3 module.


This routine registers a callback. The callback is invoked for every n instructions of the SQLite virtual machine. This is useful if you want to get called from SQLite during long-running operations, for example to update a GUI.
If you want to clear any previously installed progress handler, call the method with None for handler.
Returning a non-zero value from the handler function will terminate the currently executing query and cause it to raise an OperationalError exception.


Registers trace_callback to be called for each SQL statement that is actually executed by the SQLite backend.
The only argument passed to the callback is the statement (as string) that is being executed. The return value of the callback is ignored. Note that the backend does not only run statements passed to the Cursor.execute() methods. Other sources include the transaction management of the Python module and the execution of triggers defined in the current database.
Passing None as trace_callback will disable the trace callback.
New in version 3.3.


Using this attribute you can control what objects are returned for the TEXT data type. By default, this attribute is set to str and the sqlite3 module will return Unicode objects for TEXT. If you want to return bytestrings instead, you can set it to bytes.
You can also set it to any other callable that accepts a single bytestring parameter and returns the resulting object.
See the following example code for illustration:


Returns the total number of database rows that have been modified, inserted, or deleted since the database connection was opened.


A Cursor instance has the following attributes and methods.
Executes an SQL statement. Values may be bound to the statement using placeholders.
execute() will only execute a single SQL statement. If you try to execute more than one statement with it, it will raise a Warning. Use executescript() if you want to execute multiple SQL statements with one call.
Executes a parameterized SQL command against all parameter sequences or mappings found in the sequence seq_of_parameters. The sqlite3 module also allows using an iterator yielding parameters instead of a sequence.
Here’s a shorter example using a generator:
This is a nonstandard convenience method for executing multiple SQL statements at once. It issues a COMMIT statement first, then executes the SQL script it gets as a parameter.
sql_script can be an instance of str.
Example:
Fetches the next row of a query result set, returning a single sequence, or None when no more data is available.
Fetches the next set of rows of a query result, returning a list. An empty list is returned when no more rows are available.
The number of rows to fetch per call is specified by the size parameter. If it is not given, the cursor’s arraysize determines the number of rows to be fetched. The method should try to fetch as many rows as indicated by the size parameter. If this is not possible due to the specified number of rows not being available, fewer rows may be returned.
Note there are performance considerations involved with the size parameter. For optimal performance, it is usually best to use the arraysize attribute. If the size parameter is used, then it is best for it to retain the same value from one fetchmany() call to the next.
Fetches all (remaining) rows of a query result, returning a list. Note that the cursor’s arraysize attribute can affect the performance of this operation. An empty list is returned when no rows are available.
Close the cursor now (rather than whenever __del__ is called).
The cursor will be unusable from this point forward; a ProgrammingError exception will be raised if any operation is attempted with the cursor.
Although the Cursor class of the sqlite3 module implements this attribute, the database engine’s own support for the determination of “rows affected”/”rows selected” is quirky.
For executemany() statements, the number of modifications are summed up into rowcount.
As required by the Python DB API Spec, the rowcount attribute “is -1 in case no executeXX() has been performed on the cursor or the rowcount of the last operation is not determinable by the interface”. This includes SELECT statements because we cannot determine the number of rows a query produced until all rows were fetched.
With SQLite versions before 3.6.5, rowcount is set to 0 if you make a DELETE FROM table without any condition.
This read-only attribute provides the rowid of the last modified row. It is only set if you issued an INSERT or a REPLACE statement using the execute() method. For operations other than INSERT or REPLACE or when executemany() is called, lastrowid is set to None.
If the INSERT or REPLACE statement failed to insert the previous successful rowid is returned.
Changed in version 3.6: Added support for the REPLACE statement.
Read/write attribute that controls the number of rows returned by fetchmany(). The default value is 1 which means a single row would be fetched per call.
This read-only attribute provides the column names of the last query. To remain compatible with the Python DB API, it returns a 7-tuple for each column where the last six items of each tuple are None.
It is set for SELECT statements without any matching rows as well.
This read-only attribute provides the SQLite database Connection used by the Cursor object. A Cursor object created by calling con.cursor() will have a connection attribute that refers to con:


Read/write attribute that controls the number of rows returned by fetchmany(). The default value is 1 which means a single row would be fetched per call.


Close the cursor now (rather than whenever __del__ is called).
The cursor will be unusable from this point forward; a ProgrammingError exception will be raised if any operation is attempted with the cursor.


This read-only attribute provides the SQLite database Connection used by the Cursor object. A Cursor object created by calling con.cursor() will have a connection attribute that refers to con:


This read-only attribute provides the column names of the last query. To remain compatible with the Python DB API, it returns a 7-tuple for each column where the last six items of each tuple are None.
It is set for SELECT statements without any matching rows as well.


Executes an SQL statement. Values may be bound to the statement using placeholders.
execute() will only execute a single SQL statement. If you try to execute more than one statement with it, it will raise a Warning. Use executescript() if you want to execute multiple SQL statements with one call.


Executes a parameterized SQL command against all parameter sequences or mappings found in the sequence seq_of_parameters. The sqlite3 module also allows using an iterator yielding parameters instead of a sequence.
Here’s a shorter example using a generator:


This is a nonstandard convenience method for executing multiple SQL statements at once. It issues a COMMIT statement first, then executes the SQL script it gets as a parameter.
sql_script can be an instance of str.
Example:


Fetches all (remaining) rows of a query result, returning a list. Note that the cursor’s arraysize attribute can affect the performance of this operation. An empty list is returned when no rows are available.


Fetches the next set of rows of a query result, returning a list. An empty list is returned when no more rows are available.
The number of rows to fetch per call is specified by the size parameter. If it is not given, the cursor’s arraysize determines the number of rows to be fetched. The method should try to fetch as many rows as indicated by the size parameter. If this is not possible due to the specified number of rows not being available, fewer rows may be returned.
Note there are performance considerations involved with the size parameter. For optimal performance, it is usually best to use the arraysize attribute. If the size parameter is used, then it is best for it to retain the same value from one fetchmany() call to the next.


Fetches the next row of a query result set, returning a single sequence, or None when no more data is available.


This read-only attribute provides the rowid of the last modified row. It is only set if you issued an INSERT or a REPLACE statement using the execute() method. For operations other than INSERT or REPLACE or when executemany() is called, lastrowid is set to None.
If the INSERT or REPLACE statement failed to insert the previous successful rowid is returned.
Changed in version 3.6: Added support for the REPLACE statement.


Although the Cursor class of the sqlite3 module implements this attribute, the database engine’s own support for the determination of “rows affected”/”rows selected” is quirky.
For executemany() statements, the number of modifications are summed up into rowcount.
As required by the Python DB API Spec, the rowcount attribute “is -1 in case no executeXX() has been performed on the cursor or the rowcount of the last operation is not determinable by the interface”. This includes SELECT statements because we cannot determine the number of rows a query produced until all rows were fetched.
With SQLite versions before 3.6.5, rowcount is set to 0 if you make a DELETE FROM table without any condition.


Exception raised for errors that are related to the database.


By default you will not get any tracebacks in user-defined functions, aggregates, converters, authorizer callbacks etc. If you want to debug them, you can call this function with flag set to True. Afterwards, you will get tracebacks from callbacks on sys.stderr. Use False to disable the feature again.


The base class of the other exceptions in this module. It is a subclass of Exception.


Exception raised when the relational integrity of the database is affected, e.g. a foreign key check fails. It is a subclass of DatabaseError.


Exception raised in case a method or database API was used which is not supported by the database, e.g. calling the rollback() method on a connection that does not support transaction or has transactions turned off. It is a subclass of DatabaseError.


Exception raised for errors that are related to the database’s operation and not necessarily under the control of the programmer, e.g. an unexpected disconnect occurs, the data source name is not found, a transaction could not be processed, etc. It is a subclass of DatabaseError.


This constant is meant to be used with the detect_types parameter of the connect() function.
Setting this makes the SQLite interface parse the column name for each column it returns. It will look for a string formed [mytype] in there, and then decide that ‘mytype’ is the type of the column. It will try to find an entry of ‘mytype’ in the converters dictionary and then use the converter function found there to return the value. The column name found in Cursor.description does not include the type, i. e. if you use something like 'as "Expiration date [datetime]"' in your SQL, then we will parse out everything until the first '[' for the column name and strip the preceeding space: the column name would simply be “Expiration date”.


This constant is meant to be used with the detect_types parameter of the connect() function.
Setting it makes the sqlite3 module parse the declared type for each column it returns. It will parse out the first word of the declared type, i. e. for “integer primary key”, it will parse out “integer”, or for “number(10)” it will parse out “number”. Then for that column, it will look into the converters dictionary and use the converter function registered for that type there.


Exception raised for programming errors, e.g. table not found or already exists, syntax error in the SQL statement, wrong number of parameters specified, etc. It is a subclass of DatabaseError.


Registers a callable to convert the custom Python type type into one of SQLite’s supported types. The callable callable accepts as single parameter the Python value, and must return a value of the following types: int, float, str or bytes.


Registers a callable to convert a bytestring from the database into a custom Python type. The callable will be invoked for all database values that are of the type typename. Confer the parameter detect_types of the connect() function for how the type detection works. Note that typename and the name of the type in your query are matched in case-insensitive manner.


A Row instance serves as a highly optimized row_factory for Connection objects. It tries to mimic a tuple in most of its features.
It supports mapping access by column name and index, iteration, representation, equality testing and len().
If two Row objects have exactly the same columns and their members are equal, they compare equal.
This method returns a list of column names. Immediately after a query, it is the first member of each tuple in Cursor.description.
Changed in version 3.5: Added support of slicing.


This method returns a list of column names. Immediately after a query, it is the first member of each tuple in Cursor.description.


The version number of the run-time SQLite library, as a string.


The version number of the run-time SQLite library, as a tuple of integers.


The version number of this module, as a string. This is not the version of the SQLite library.


The version number of this module, as a tuple of integers. This is not the version of the SQLite library.