标题：MySQLi
需求
要使用本扩展库中的函数，必须在编译 PHP 时加入 mysqli 扩展的支持。 
Note: mysqli 扩展库是设计用于同 MySQL 4.1.3 或更高版本协同工作的。对之前版本，请参考 MySQL 扩展库文档。
安装
要安装 PHP 的 mysqli 扩展，配置时加上 --with-mysqli=mysql_config_path/mysql_config。其中 mysql_config_path 表示 mysql_config 程序的路径，该程序随 MySQL 大于 4.1 版本一起发布。 
如果要同时安装 mysql 和 mysqli 扩展，必须使用同一个客户端库以避免冲突。 
运行时配置
这些函数的行为受 php.ini 的影响。
MySQLi 配置选项 名称 默认值 可修改范围 更新日志 
mysqli.max_links "-1" PHP_INI_SYSTEM 自 PHP 5.0.0 起可用。 
mysqli.default_port "3306" PHP_INI_ALL 自 PHP 5.0.0 起可用。 
mysqli.default_socket NULL PHP_INI_ALL 自 PHP 5.0.0 起可用。 
mysqli.default_host NULL PHP_INI_ALL 自 PHP 5.0.0 起可用。 
mysqli.default_user NULL PHP_INI_ALL 自 PHP 5.0.0 起可用。 
mysqli.default_pw NULL PHP_INI_ALL 自 PHP 5.0.0 起可用。 
以上 PHP_INI_* 常量的进一步细节及定义，见怎样修改配置设定一节。 
以下是配置选项的简要解释。
mysqli.max_links integer 
每个进程的 MySQL 连接的最大数目。 
mysqli.default_port string 
The default TCP port number to use when connecting to the database server if no other port is specified. If no default is specified, the port will be obtained from the MYSQL_TCP_PORT environment variable, the mysql-tcp entry in /etc/services or the compile-time MYSQL_PORT constant, in that order. Win32 will only use the MYSQL_PORT constant. 
mysqli.default_socket string 
The default socket name to use when connecting to a local database server if no other socket name is specified. 
mysqli.default_host string 
The default server host to use when connecting to the database server if no other host is specified. Doesn't apply in safe mode. 
mysqli.default_user string 
The default user name to use when connecting to the database server if no other name is specified. Doesn't apply in safe mode. 
mysqli.default_pw string 
The default password to use when connecting to the database server if no other password is specified. Doesn't apply in safe mode.
预定义类
mysqli表达了 PHP 和 MySQL 数据库之间的连接。 
构造函数
mysqli - 构造一个新的 mysqli 对象
方法
autocommit - 打开或关闭自动提交的数据库选项
change_user - 改变指定的数据库连接的用户
character_set_name - 返回数据库连接的默认字符集
close - 关闭一个之前打开的连接
commit - 提交当前事务
connect - 打开一个到 MySQL 数据库服务器的新连接
debug - 执行排错操作
dump_debug_info - 取得排错信息
get_client_info - 返回客户端版本
get_host_info - 返回连接使用的类型
get_server_info - 返回 MySQL 服务器的版本
get_server_version - 返回 MySQL 服务器的版本
init - 初始化 mysqli 对象
info - 取得最近执行的查询的信息
kill - 要求服务器停止一个 mysql 线程
multi_query - 执行多个查询
more_results - check if more results exist from currently executed multi-query
next_result - reads next result from currently executed multi-query
options - set options
ping - pings a server connection or reconnects if there is no connection
prepare - prepares a SQL query
query - performs a query
real_connect - attempts to open a connection to MySQL database server
escape_string - escapes special characters in a string for use in a SQL statement, taking into account the current charset of the connection
rollback - rolls back the current transaction
select_db - selects the default database
set_charset - sets the default client character set
ssl_set - sets ssl parameters
stat - gets the current system status
stmt_init- initializes a statement for use with mysqli_stmt_prepare
store_result - transfers a resultset from last query
thread_safe - returns whether thread safety is given or not
use_result - transfers an unbuffered resultset from last query
属性
affected_rows - gets the number of affected rows in a previous MySQL operation
client_info - returns the MySQL client version as a string
client_version - returns the MySQL client version as an integer
errno - returns the error code for the most recent function call
error - returns the error string for the most recent function call
field_count - returns the number of columns for the most recent query
host_info - returns a string representing the type of connection used
info - retrieves information about the most recently executed query
insert_id - returns the auto generated id used in the last query
protocol_version - returns the version of the MySQL protocol used
server_info - returns a string that represents the server version number
server_version - returns the version number of the server as an integer
sqlstate - returns a string containing the SQLSTATE error code for the last error
thread_id - returns the thread ID for the current connection
warning_count - returns the number of warnings generated during execution of the previous SQL statementmysqli_stmt表达了一个预备好的语句。 
方法
bind_param - binds variables to a prepared statement
bind_result - binds variables to a prepared statement for result storage
close - closes a prepared statement
data_seek - seeks to an arbitrary row in a statement result set
execute - executes a prepared statement
fetch - fetches result from a prepared statement into bound variables
free_result - frees stored result memory for the given statement handle
prepare - prepares a SQL query
reset - resets a prepared statement
result_metadata - retrieves a resultset from a prepared statement for metadata information
send_long_data - sends data in chunks
store_result - buffers complete resultset from a prepared statement
属性
affected_rows - returns affected rows from last statement execution
errno - returns errorcode for last statement function
error - returns errormessage for last statement function
field_count - returns the number of columns in a result set
id - returns the statement identifier
insert_id - returns the value generated for an AUTO_INCREMENT column by the prepared statement
num_rows - returns the number of rows in the result set
param_count - returns number of parameter for a given prepare statement
sqlstate - returns a string containing the SQLSTATE error code for the last statement functionmysqli_result表达了对数据库的查询所返回的结果集。 
方法
close - closes resultset
data_seek - moves internal result pointer
fetch_array - fetches a result row as an associative array, a numeric array, or both.
fetch_assoc - fetches a result row as an associative array
fetch_field - gets column information from a resultset
fetch_fields - gets information for all columns from a resulset
fetch_field_direct - gets column information for specified column
fetch_object - fetches a result row as an object
fetch_row - gets a result row as an enumerated array
field_seek - set result pointer to a specified field offset
free_result - frees result memory
属性
current_field - returns offset of current fieldpointer
field_count - returns number of fields in resultset
lengths - returns an array of columnlengths
num_rows - returns number of rows in resultset
type - returns MYSQLI_STORE_RESULT or MYSQLI_USE_RESULT
预定义常量
MySQLi 常量 名称 说明 
MYSQLI_READ_DEFAULT_GROUP (integer) Read options from the named group from `my.cnf' or the file specified with MYSQLI_READ_DEFAULT_FILE 
MYSQLI_READ_DEFAULT_FILE (integer) Read options from the named option file instead of from my.cnf 
MYSQLI_OPT_CONNECT_TIMEOUT (integer) Connect timeout in seconds 
MYSQLI_OPT_LOCAL_INFILE (integer) Enables command LOAD LOCAL INFILE 
MYSQLI_INIT_COMMAND (integer) Command to execute when connecting to MySQL server. Will automatically be re-executed when reconnecting. 
MYSQLI_CLIENT_SSL (integer) Use SSL (encrypted protocol). This option should not be set by application programs; it is set internally in the MySQL client library 
MYSQLI_CLIENT_COMPRESS (integer) Use compression protocol 
MYSQLI_CLIENT_INTERACTIVE (integer) Allow interactive_timeout seconds (instead of wait_timeout seconds) of inactivity before closing the connection. The client's session wait_timeout variable will be set to the value of the session interactive_timeout variable. 
MYSQLI_CLIENT_IGNORE_SPACE (integer) Allow spaces after function names. Makes all functions names reserved words. 
MYSQLI_CLIENT_NO_SCHEMA (integer) Don't allow the db_name.tbl_name.col_name syntax. 
MYSQLI_CLIENT_MULTI_QUERIES (integer) 
MYSQLI_STORE_RESULT (integer) For using buffered resultsets 
MYSQLI_USE_RESULT (integer) For using unbuffered resultsets 
MYSQLI_ASSOC (integer) Columns are returned into the array having the fieldname as the array index. 
MYSQLI_NUM (integer) Columns are returned into the array having an enumerated index. 
MYSQLI_BOTH (integer) Columns are returned into the array having both a numerical index and the fieldname as the associative index. 
MYSQLI_NOT_NULL_FLAG (integer) Indicates that a field is defined as NOT NULL 
MYSQLI_PRI_KEY_FLAG (integer) Field is part of a primary index 
MYSQLI_UNIQUE_KEY_FLAG (integer) Field is part of a unique index. 
MYSQLI_MULTIPLE_KEY_FLAG (integer) Field is part of an index. 
MYSQLI_BLOB_FLAG (integer) Field is defined as BLOB 
MYSQLI_UNSIGNED_FLAG (integer) Field is defined as UNSIGNED 
MYSQLI_ZEROFILL_FLAG (integer) Field is defined as ZEROFILL 
MYSQLI_AUTO_INCREMENT_FLAG (integer) Field is defined as AUTO_INCREMENT 
MYSQLI_TIMESTAMP_FLAG (integer) Field is defined as TIMESTAMP 
MYSQLI_SET_FLAG (integer) Field is defined as SET 
MYSQLI_NUM_FLAG (integer) Field is defined as NUMERIC 
MYSQLI_PART_KEY_FLAG (integer) Field is part of an multi-index 
MYSQLI_GROUP_FLAG (integer) Field is part of GROUP BY 
MYSQLI_TYPE_DECIMAL (integer) Field is defined as DECIMAL 
MYSQLI_TYPE_NEWDECIMAL (integer) Precision math DECIMAL or NUMERIC field (MySQL 5.0.3 and up) 
MYSQLI_TYPE_BIT (integer) Field is defined as BIT (MySQL 5.0.3 and up) 
MYSQLI_TYPE_TINY (integer) Field is defined as TINYINT 
MYSQLI_TYPE_SHORT (integer) Field is defined as INT 
MYSQLI_TYPE_LONG (integer) Field is defined as INT 
MYSQLI_TYPE_FLOAT (integer) Field is defined as FLOAT 
MYSQLI_TYPE_DOUBLE (integer) Field is defined as DOUBLE 
MYSQLI_TYPE_NULL (integer) Field is defined as DEFAULT NULL 
MYSQLI_TYPE_TIMESTAMP (integer) Field is defined as TIMESTAMP 
MYSQLI_TYPE_LONGLONG (integer) Field is defined as BIGINT 
MYSQLI_TYPE_INT24 (integer) Field is defined as MEDIUMINT 
MYSQLI_TYPE_DATE (integer) Field is defined as DATE 
MYSQLI_TYPE_TIME (integer) Field is defined as TIME 
MYSQLI_TYPE_DATETIME (integer) Field is defined as DATETIME 
MYSQLI_TYPE_YEAR (integer) Field is defined as YEAR 
MYSQLI_TYPE_NEWDATE (integer) Field is defined as DATE 
MYSQLI_TYPE_ENUM (integer) Field is defined as ENUM 
MYSQLI_TYPE_SET (integer) Field is defined as SET 
MYSQLI_TYPE_TINY_BLOB (integer) Field is defined as TINYBLOB 
MYSQLI_TYPE_MEDIUM_BLOB (integer) Field is defined as MEDIUMBLOB 
MYSQLI_TYPE_LONG_BLOB (integer) Field is defined as LONGBLOB 
MYSQLI_TYPE_BLOB (integer) Field is defined as BLOB 
MYSQLI_TYPE_VAR_STRING (integer) Field is defined as VARCHAR 
MYSQLI_TYPE_STRING (integer) Field is defined as CHAR 
MYSQLI_TYPE_GEOMETRY (integer) Field is defined as GEOMETRY 
MYSQLI_NEED_DATA (integer) More data available for bind variable 
MYSQLI_NO_DATA (integer) No more data available for bind variable 
MYSQLI_DATA_TRUNCATED (integer) Data truncation occurred. Available since PHP 5.1.0 and MySQL 5.0.5.
例子
在 MySQLI 文档中的所有例子都使用了来自 MySQL AB 的 world 数据库。数据库 world 可以在此地址下载： http://dev.mysql.com/get/Downloads/Manual/world.sql.gz/from/pick。 
范例
mysql的连接方式
一、面向对象
<?php$mysqli =new mysqli("localhost", "my_user", "my_password", "world"); //实例化对象/* check connection */ if (mysqli_connect_errno()) { printf("Connect failed: %s\n", mysqli_connect_error()); exit();}printf("Host information: %s\n", $mysqli->host_info);/* close connection */$mysqli->close();?> 
二、面向过程
<?php$link = mysqli_connect("localhost", "my_user", "my_password", "world");/* check connection */ if (!$link) { printf("Connect failed: %s\n", mysqli_connect_error()); exit();}printf("Host information: %s\n", mysqli_get_host_info($link));/* close connection */mysqli_close($link);?>