bintang 0.2.6
A tiny and temporary db for quick data cleansing and transformation.
Keywords: data table tool

=======
Bintang
=======
A tiny and temporary db for quick data cleansing and transformation.
It is a high-level Python coding and would help any Pythonistas up to speed with ETL work.

.. contents:: Table of Contents
   :depth: 2

------------------
How to get started
------------------


Requirements
------------
1. Python 3.10 or higher

Some functions require other packages to work. These packages can be installed from pypi using the pip package manager.
Here is a list of the functions and its dependencies:


.. list-table::
   :widths: 40 50
   :header-rows: 1

   * - Functions
     - Packages
   * - create_linked_table(), read_sql() and to_sql()
     - pyodbc or psycopg (postgresql specific)
   * - read_excel()
     - openpyxl (xlsx) and xlrd (xls)
   * - to_excel()
     - openpyxl (xlsx) and xlwt (xls)




Installation
------------

.. code-block:: python

   pip install bintang


Examples of Usage
-----------------

.. code-block:: python

   from bintang import Bintang # import the package
   bt = Bintang()              # bintang object created

   bt.create_table('Person')  
   print(bt  )
   # {  
   #    "name": null,  
   #    "tables": [  
   #    "Person"  
   #    ]  
   # }  


Use insert function to populate a table. The parameters are record and columns.

.. code-block:: python

   # Create a couple of tables and use insert function to insert data.
   bt.create_table('Person') 

   bt['Person'].insert([1,'John','Smith','1 Station St'], ['id','name','surname','address'])
   bt['Person'].insert([2,'Jane','Brown','Digging','8 Parade Rd'], ['id','name','surname','hobby','address'])
   bt['Person'].insert([3,'Okie','Dokie','7 Ocean Rd'], ['id','name','surname','Address'])
   bt['Person'].insert((4,'Maria','Digging','7 Heaven Ave'), ('id','name','hobby','Address'))
   bt['Person'].insert((5,'Bing','Digging',None), ('id','name','hobby','Address'))

   bt.create_table("FishingClub")
   bt['FishingClub'].insert(['Ajes','Freeman','Active'], ['FirstName','LastName','Membership'])
   bt['FishingClub'].insert(['John','Smith','Active'], ['FirstName','LastName','Membership'])
   bt['FishingClub'].insert(['Jane','Brown','Active'], ['FirstName','LastName','Membership'])
   bt['FishingClub'].insert(['Nutmeg','Spaniel','Active'], ['FirstName','LastName','Membership'])
   bt['FishingClub'].insert(['Zekey','Pokey','Active'], ['FirstName','LastName','Membership'])

Loop your data using iterrows function. This will loop through all the rows one by one in a Python dict.

.. code-block:: python

   for idx, row in bt['Person'].iterrows():
       print(idx, row)  
  
   # 1 {'id': 1, 'name': 'John', 'surname': 'Smith', 'address': '1 Station St', 'hobby': None}
   # 2 {'id': 2, 'name': 'Jane', 'surname': 'Brown', 'address': '8 Parade Rd', 'hobby': 'Digging'}
   # 4 {'id': 3, 'name': 'Okie', 'surname': 'Dokie', 'address': '7 Ocean Rd', 'hobby': None}
   # 4 {'id': 4, 'name': 'Maria', 'surname': None, 'address': '7 Heaven Ave', 'hobby': 'Digging'}
   # 5 {'id': 5, 'name': 'Bing', 'surname': None, 'address': None, 'hobby': 'Digging'}

If the table is small, you can use print() function to output the records to terminal.

.. code-block:: python

   Person.print()
   #                           Table: Person
   # --------------+---------+-----------+----------------+-----------
   #       id      |   name  |  surname  |    address     |   hobby
   # --------------+---------+-----------+----------------+-----------
   #             1 | John    | Smith     | 1 Station St   | None
   #             2 | Jane    | Brown     | 8 Parade Rd    | Digging
   #             3 | Okie    | Dokie     | 7 Ocean Rd     | None
   #             4 | Maria   | None      | 7 Heaven Ave   | Digging
   #             5 | Bing    | None      | None           | Digging
   # --------------+---------+-----------+----------------+-----------
   # (5 rows)
   


You should notice that all columns now have been normalised for each row, even though all records have not used all column names during insertion.\
When the 1st record (idx 0) is inserted, four columns created. id, name, age and address.
When insert 4th record is inserted (idx 3), a hobby column added.
 
Inspect Person table column list. You can also use function table.get_columns() to list all columns.

.. code-block:: python

   print(bt['Person'])
   # {  
   #   "name": "Person",  
   #   "columns": [
   #       {"id": 0,"name": "id"},  
   #       {"id": 1,"name": "name"},  
   #       {"id": 2,"name": "age"},  
   #       etc...
   # }

Use update function to change the data. The function signature is table.update(column, value, where=None). The value and where parameters can use lambda function argument for smarter expression.

.. code-block:: python

   bt['Person'].update('age', 10, where=lambda row: row['name']=='Maria') 

Retrieve the row stored at the 3rd index by passing 3 inside the list next to table object.

.. code-block:: python

   bt['Person'][3] 
   # {'id': 4, 'name': 'Maria', 'age': 10, 'address': '7 Heaven Ave', 'hobby': 'Digging'} 



----------------
Common Functions
----------------

We are going to provide some functions that may be needed most when working with Bintang objects.



Bintang.read_excel(wb, sheetnames=None)
---------------------------------------

Read an Excel file and create Bintang tables. The first row will be assumed as column header.
Go to Bintang.Table.read_excel() to read a single sheet and populate the data into created table.
Use openpyxl workbook (wb) to read from xlsx, or use xlrd wb to read from xls.
Before using openpyxl or xlrd package, you must install the packages. Below is an example on how to install the packge from a terminal.

.. code-block:: console

  C:\project_dir>pip install openpyxl
  C:\project_dir>pip install xlrd


:path: an excel file path to read from.
:sheetname: a list of sheets that only needed to be read. If not specified all available sheets will be read (default).

.. code-block:: python

   from openpyxl import Workbook
   ...
   wb = load_workbook('/path/to/file.xlsx',  read_only=True, data_only=True)
   bt.read_excel(wb, sheetnames)



Bintang.read_dict(dict_obj, tablepaths=None, root='/', path_sep='/')
--------------------------------------------------------------------
Read dictionary object and create a table or more according to hierarchy paths contained in the object.

:dict_obj: a python dictionary object
:tablepaths: a list of paths which contains a list of objects (equivalent to records)
:root: name for root table equivalent to root node in the dictionary
:path_sep: separator for paths


.. code-block:: python
   
   # other module import
   # ...
   import bintang

   # example dict object
   dict_obj = {
        'Page': 100,
        'Time': '2033-09-05T00:00:00Z',
        'Person': [
            {'id': 1,'name': 'John','surname': 'Smith',
                'Address': {'number': 1, 'street': 'Station','street_type': 'Street'}
            },
            {'id': 2,'name': 'Jane','surname': 'Brown',
                'Address': {'number': 8,'street': 'Parade','street_type': 'Road'}
            }
        ],
        'PersonDetails': [
            {'person_id': '1', 'hobby': 'Blogging','is_meat_eater': True
            },
            {'person_id': '2','hobby': 'Reading','is_meat_eater': None,
                'LuckyDays': [13,17,19]
            }
        ]
   }
   bt = bintang.Bintang()
   bt.read_dict(dict_obj)

   print(bt) # show bt tables
   # {
   #    "name": null,
   #    "tables": [
   #       "/",
   #       "//Person",
   #       "//Person/Address",
   #       "//PersonDetails",
   #       "//PersonDetails/LuckyDays"
   #    ]
   # }

   # loop through root table ('/')
   for idx, row in bt['/'].iterrows():
       print(idx, row)
   # 0 {'Page:': 100, 'Time': '2033-09-05T00:00:00Z'}

   # loop through  //Person table.
   for idx, row in bt['//Person'].iterrows():
       print(idx, row)
   # 0 {'Person': 0, 'id': 1, 'name': 'John', 'surname': 'Smith'}
   # 1 {'Person': 1, 'id': 2, 'name': 'Jane', 'surname': 'Brown'} 

   # print //Person/Address table. Because this table under //Person, then each record will have their own 
   # reference to //Person table.
   
   bt['//Person/Address'].print()

   #                      Table: //Person/Address
   # -----------+--------------+--------------+-----------+---------------
   #   Address  |    Person    |    number    |   street  |  street_type
   # -----------+--------------+--------------+-----------+---------------
   #  Address   |            0 |            1 | Station   | Street
   #  Address   |            1 |            8 | Parade    | Road
   # -----------+--------------+--------------+-----------+---------------
   # (2 rows)

Please note that since dictionary can contain complex hierarchy paths and still valid (eg. system configuration), then a further transformation is required. A dictionary that consists of a list of record objects can be transformed to Bintang table straight away.
   


Bintang.read_json(json_str, tablepaths=None, root='/', path_sep='/')
--------------------------------------------------------------------
Read JSON string and create a table or more according to hierarchy paths contained in the object.
This function merely wraps read_dict() and use json.loads to decode json string argument to dictionary.

:json_str: a json string
:tablepaths: a list of paths which contains a list of objects (equivalent to records).
:root: name for root table equivalent to root node in the dictionary
:path_sep: separator for paths


.. code-block:: python
   
   # other module import
   # ...
   import bintang
   
   # example json data
   json_str = '{"Page:": 100, "Time": "2033-09-05T00:00:00Z", \
               "Person": [{"id": 1, "name": "John", "surname": "Smith", \
                            "Address": {"number": 1, "street": "Station", "street_type": "Street"}}, \
                          {"id": 2, "name": "Jane", "surname": "Brown", \
                            "Address": {"number": 8, "street": "Parade", "street_type": "Road"}}], \
               "PersonDetails": [{"person_id": "1", "hobby": "Blogging", "is_meat_eater": true}, \
                                 {"person_id": "2", "hobby": "Reading", "is_meat_eater": null, \
                                   "LuckyDays": [13, 17, 19]}]}'

   bt = bintang.Bintang()
   bt.read_json(json_str)

   print(bt) # show bt tables
   # see read_dict() above to navigate the tables
   

Bintang.read_xml()
------------------
This is just a placeholder. To read XML data, you may use xml.etree.ElementTree or lxml package or xmltodict to parse the XML data and convert it to a dictionary object, then use read_dict() function to create Bintang tables.
Here is an example to read XML data and convert it to Bintang tables.

.. code-block:: python

   import bintang
   import xmltodict


   # example xml data that have two tables from its paths.
   # they are Person (parent table) and Address (child table)
   xml_str = """<root>
                  <Person>
                     <id>1</id>
                     <name>John</name>
                     <surname>Smith</surname>
                     <Address>
                           <number>1</number>
                           <street>Station</street>
                           <street_type>Street</street_type>
                     </Address>
                  </Person>
                  <Person>
                     <id>2</id>
                     <name>Jane</name>
                     <surname>Brown</surname>
                     <Address>
                           <number>8</number>
                           <street>Parade</street>
                           <street_type>Road</street_type>
                     </Address>
                  </Person>
               </root>"""

   dict_obj = xmltodict.parse(xml_str)
   bt = bintang.Bintang()
   bt.read_dict(dict_obj)

   print(bt) # show bt tables

   # print each table
   for tbl_name in bt.get_tables():
      bt[tbl_name].print()



Bintang.Table.blookup(lkp_table, on, ret_columns)
-------------------------------------------------

Return one or more columns from lookup table.

:lkp_table: lookup table
:on: lookup key tuples
:ret_columns: lookup columns to be returned


.. code-block:: python
    
   # using tables from Example of Usage section above.
   bt['Person'].blookup('FishingClub')], \
       [('name','FirstName')], \
       ['Membership'])

   # check results
   for idx, row in bt['Person'].iterrows(['name','Membership']):
       print(idx, row)

   # 0 {'name': 'John', 'Membership': 'Active'}
   # 1 {'name': 'Jane', 'Membership': 'Active'}
   # 2 {'name': 'Okie', 'Membership': None}
   # 3 {'name': 'Maria', 'Membership': None}    
   
We can see only John and Jane got the membership because their names exists in both tables.


Bintang.Table.cmprows(lkp_table, on, min_keys=None, full=True)
--------------------------------------------------------------

Compare rows from current table against lkp_table and yield matching row indexes and matched columns.
blookup function use this function internally to find the matching rows.

:lkp_table: lookup table
:on: a list of pair columns used for the comparison. If None, will compare all columns that exist in both tables.
:min_keys: minimum number of matched columns to consider as a match.
:full: if True, will compare all rows, otherwise will stop at the first match.


.. code-block:: python

   # using tables from Example of Usage section above.
   for lidx, ridx, matched_cols in bt['Person'].cmprows('FishingClub'
                                        ,on = [('name', 'FirstName'), ('surname', 'LastName')]
                                        ):
       print(lidx, ridx, matched_cols)
   # 1 2 [('name', 'FirstName'), ('surname', 'LastName')]
   # 2 3 [('name', 'FirstName'), ('surname', 'LastName')]



Bintang.Table.groupby(columns, drop_none=True, group_count=False, counts=None, sums=None, mins=None, maxs=None, means=None, group_concat=None)
----------------------------------------------------------------------------------------------------------------------------------------------

Return grouped rows based upon the value of columns.

:columns: a list of columns that is used to group the data.
:drop_none: if True, to drop/exclude the group if all columns hold None.
:group_count: if True, create row count from group columns.
:group_concat: a column to create group_concat like mysql.
:counts: a list of columns to create count column(s)
:sums: a list of columns to create sum column(s)
:mins: a list of columns to create min column(s)
:maxs: a list of columns to create max column(s) 

.. code-block:: python

   bt.create_table('Product') # this will be our basis table for grouping
   p = bt['Product'] # assign p as the table
   p.insert({'id':1, 'brand': 'Shimano', 'class':'rod', 'name':'Extraction','price':299})
   p.insert({'id':2, 'brand': 'Shimano', 'class':'rod', 'name':'Zodias Travel','price':399})
   p.insert({'id':3, 'brand': 'Ugly Stik', 'class':'rod', 'name':'Balance II','price':63.99})
   p.insert({'id':4, 'brand': 'Shimano', 'class':'rod', 'name':'Zodias Travel','price':399})
   p.insert({'id':5, 'brand': 'Shimano', 'class':'reel', 'sub class': 'spinning', 'name':'Sedona F1','price':99.00})
   p.insert({'id':6, 'brand': 'Shimano', 'class':'reel', 'sub class':'spinning', 'name':'FX Series 4000','price':54.99})

   grouped = p.groupby(['brand', 'class'], group_count=True)

   grouped.print()
   #              Table: grouped
   # -------------+---------+---------------
   #     brand    |  class  |  group_count
   # -------------+---------+---------------
   #  Shimano     | rod     |             3
   #  Ugly Stik   | rod     |             1
   #  Shimano     | reel    |             2
   # -------------+---------+---------------
   # (3 rows)

   grouped = p.groupby(['brand'], group_concat='id', sums=['price']) # another example

   grouped.print()
   #                     Table: grouped
   # -------------+-------------------+-------------------
   #     brand    |    group_concat   |     sum_price
   # -------------+-------------------+-------------------
   #  Shimano     |   [1, 2, 4, 5, 6] |           1250.99
   #  Ugly Stik   |               [3] |             63.99
   # -------------+-------------------+-------------------
   # (2 rows)   



Bintang.Table.innerjoin(right_table, on, into=None, out_leftcolumns=None, out_rightcolumns=None)
------------------------------------------------------------------------------------------------

Return a new table from an inner join operation.

:right_table: name of right table or the second table.
:on: a list of pair columns used for the join.
:into: a new table name to hold the result.
:out_leftcolumns: columns output from left table. If not specified then it will return all columns.
:out_rightcolumns: columns outpout from right table. If not specified then it will return all columns.

.. code-block:: python

   bt.create_table('Person') # This will be a left table
   # insert some record here. See insert below for an example.
   # ...

   bt.create_table('FishingClub') # this will be a right table
   # insert some records here. See insert below for an example.
   # ...

   # let's match the two tables for their firt name and last name.
   res = bt.innerjoin('Person'                                       # left table
                     ,'FishingClub'                                  # right table
                     ,[('name','FirstName'), ('surname','LastName')] # on
                     ,into='Fisherman'                               
                     ,out_lcolumns=['name','address']
                     ,out_rcolumns=['Membership']
                     )

   # check the result. you can loop through 'Fisherman' or res.
   for idx, row in bt['Fisherman'].iterrows():
      print(idx, row)



Bintang.Table.insert(record, columns=None)
------------------------------------------
Insert a record into a table.

:record: a list/tuple of data. Or a dict where key=column, value=record
:columns: a list/tuple of columns (in the same order as in the record)

.. code-block:: python

   bt.create_table('Person') 
   p = bt.get_table('Person') # get table object for Person
   # insert data directly from table object instead throug bt object.
   p.insert([1,'John','Smith','1 Station St'], ['id','name','surname','address'])
   p.insert([2,'Jane','Brown','Digging','8 Parade Rd'], ['id','name','surname','hobby','address'])
   p.insert([3,'Okie','Dokie','7 Ocean Rd'], ['id','name','surname','Address'])
   p.insert((4,'Maria','Digging','7 Heaven Ave'), ('id','name','hobby','Address'))
   p.insert((5,'Bing','Digging',None), ('id','name','hobby','Address'))

   bt.create_table('FishingClub')
   # lets make a list of columns so we can pass it to insert.
   columns = ['FirstName','LastName','Membership']
   bt['FishingClub'].insert(['Ajes','Freeman','Active'], columns)
   bt['FishingClub'].insert(['John','Smith','Active'], columns)
   bt['FishingClub'].insert(['John','Brown','Active'], columns)
   bt['FishingClub'].insert(['Okie','Dokie','Active'], columns)
   bt['FishingClub'].insert(['Zekey','Pokey','Active'], columns)


   bt.create_table("Product")
   prod = bt['Product']
   # example of assigning a dictionary argument for record parameter.
   prod.insert({'id':1, 'name':'Hook','price':1.60})
   prod.insert({'id':2, 'name':'Sinker','price':1.20})
   prod.insert({'id':3, 'name':'Reels','price':75})



Bintang.Table.iterrows(columns=None, row_type='dict')
-----------------------------------------------------

Loop through Bintang table's rows and yield index and row. Row can be called out as dict (default) or list.

:columns: a list of columns to output. If None, will output all columns.
:row_type: either 'dict' (default) or 'list'.

.. code-block:: python

   for idx, row in bt['tablename'].iterrows():
       # do something with idx or row
       print(idx, row) 


.. _read_csv:

Bintang.Table.read_csv(path, delimiter=',', quotechar='"', header_row=1)
------------------------------------------------------------------------

Read csv file and populate its records to table.

:path: a csv file path to read from.
:delimiter: field seperator, by default it'll accept a comma character.
:header_row: the row number that contains column name or label.

.. code-block:: python

   ## example data in  csv file
   # "id","name","surname","address","hobby"
   # "1","John","Smith","1 Station St",""
   # "2","Jane","Brown","8 Parade Rd","Digging"
   
   bt.create_table('Person')
   bt['Person'].read('/path/to/file.csv') 
   bt['Person'].print()

   #                          Table: Person
   # ------+---------+-----------+----------------+-----------
   #   id  |   name  |  surname  |    address     |   hobby
   # ------+---------+-----------+----------------+-----------
   #  1    | John    | Smith     | 1 Station St   |
   #  2    | Jane    | Brown     | 8 Parade Rd    | Digging
   # ------+---------+-----------+----------------+-----------
   # (2 rows)



Bintang.Table.read_excel(wb, sheetname, header_row=1)
-----------------------------------------------------

Read an Excel file into Bintang table.
Use openpyxl workbook (wb) to read from xlsx, or use xlrd wb to read from xls.
Before using openpyxl or xlrd package, you must install the packages. Below is an example on how to install the packge from a terminal.

.. code-block:: console

  C:\project_dir>pip install openpyxl
  C:\project_dir>pip install xlrd


:wb: a workbook object
:sheetname: the sheetname to read from.
:header_row: the row number that contains column name or label.

.. code-block:: python

   ### to read from xlsx
   from openpyxl import load_workbook
   ...
   wb = load_workbook('/path/to/file.xlsx', read_only=True, data_only=True)
   bt.create_table('Person')
   bt['Person'].read_excel(wb, 'Sheet1')
   

   ### to read from xls
   import xlrd
   ...
   wb = xlrd.open_workbook('/path/to/file.xlsx')
   bt.create_table('Person')
   bt['Person'].read_excel(wb, 'Sheet1')
   

.. _read_sql:

Bintang.Table.read_sql(conn, sql_str=None, params=None)
-------------------------------------------------------

Read sql table/statement and populate the data to Bintang table.
If you need to read sql table/statement without populating data then you must use create_sql_linked_table_ function.
This function requires pyodbc or psycopg (postgresql specific) connection, therefore you must install the required package.
Below is an example to install the package from a terminal.


.. code-block:: console

   C:\project_dir>pip install pyodbc
   C:\project_dir>pip install psycopg

:conn: pyodbc database connection
:sql_str: sql query, if none it will select * from a same sql table name.
:params: sql parameters

.. code-block:: python

   import bintang
   import pyodbc
   
   # connect to sql server
   conn_str = "DRIVER={ODBC Driver 17 for SQL Server};SERVER=localhost;PORT=1443;DATABASE=test;Trusted_Connection=yes;"
   conn = pyodbc.connect(conn_str)
   sql_str = "SELECT * FROM Person WHERE LastName=?"
   params = ('Dokey')

   bt = bintang.Bintang()
   bt.create_table('Person')
   bt['Person'].read_sql(conn, sql_str, params)

   for idx, row in bt['Person'].iterrows():
       print(idx, row)
       # would print {'ID': 3, 'FirstName': 'Okie', 'LastName': 'Dokey', 'address': '7 Ocean Rd'}

   conn.close()    



Bintang.table.to_csv(path, columns=None, index=False, delimiter=',', quotechar='"', quoting=0)
----------------------------------------------------------------------------------------------

Write bintang table to a csv file.

:path: a csv file path to write to.
:index: write row index if it sets True.
:delimiter: field seperator
:quotechar: a character to quote the data
:quoting: the csv enum for quoting, csv.QUOTE_MINIMAL or  0, csv.QUOTE_ALL or 1, csv.QUOTE_NONNUMERIC or 2, csv.QUOTE_NONE or 3

Notes: setting quoting parameter properly will provide correct value to be presented in csv even if the value containing a delimiter character.

.. code-block:: python

   bt['tablename'].to_csv('/path/to/file.csv')

                  

Bintang.Table.to_excel(wb, path, columns=None, index=False, sheet_title=None)
-----------------------------------------------------------------------------

Write Bintang table to an Excel file.
Use openpyxl workbook (wb) to save as xlxs, or xlwt to save as xls.
Before using openpyxl or xlwt package, you must install the packages. Below is an example on how to install the packge from a terminal.

.. code-block:: console

  C:\project_dir>pip install openpyxl
  C:\project_dir>pip install xlwt


:path: an excel file path to write to.
:columns: a list of columns to save, if None then all columns will be saved.
:index: write row index if it sets True.
:sheet_title: the sheet title, if None then table name will be passed.

.. code-block:: python

   ### to target xlxs
   from openpyxl import Workbook  # import a Workbook class
   ...
   wb = Worbook() # create a wb class
   bt['tablename'].to_excel(wb, '/path/to/file.xlsx')

   ### to target xls
   from xlwt import Workbook
   ...
   wb = Workbook()
   bt['tablename'].to_excel(wb, '/path/to/file.xls')



Bintang.Table.to_json()
-----------------------
This is just a placeholder. Python make it easy when serializing a dict object to JSON. Conversion would be done by built-in json.JSONEncoder().
Here an example of using our to_dict() function then use build-in module json to convert/export dict to JSON.

.. code-block:: python

   # other modules here
   # ...
   import json
   
   # other codes here
   # ...

   dict_obj = bt['table_name'].to_dict()

   # example to serialise dict_obj to json string
   json_str = json.dumps(dict_obj)
   # use json_str here!
   # ...


   # example to write dict_obj to a json file
   with open ('myfile.json', 'w') as fp:
       json.dump(dict_obj, fp) # this would serialise dict_obj into myfile.json



Bintang.Table.to_sql(conn, table, columns=None, schema=None, method='prep', max_rows = 1)
-----------------------------------------------------------------------------------------

Insert records into sql table.
This function requires pyodbc or psycopg (postgresql specific) connection, therefore you must install the required package.
Below is an example to install the package from a terminal.

.. code-block:: console

   C:\project_dir>pip install pyodbc
   C:\project_dir>pip install psycopg

:conn: pyodbc database connection
:table: the table name in the sql database
:columns: If a dictionary then a columns mapping where the key is sql column (destination) and the value is bintang columns (source). If a list, column mapping will be created automatically assuming source columns and destination columns are the same. If not provided it assumes that user wants to insert all the columns from the table.
:schema: the schema name the sql table belongs to.
:method: 'prep' to use prepared statement (default) or 'string' to use sql string. To avoid sql injection, never use string method when the datasource is external or not known.
:max_rows: maximum rows per batch insert. Allowed value would be from 1 to 1000. Insert more then 1 record when using prep require all data in a column to use the same type, otherwise will raise error.

.. code-block:: python
   
   import bintang
   import pyodbc

   bt = bintang.Bintang()
   bt.create_table('Person')
   person = bt.get_table('Person')
   person.insert([1,'John','Smith','1 Station St'], ['id','name','surname','address'])
   person.insert([2,'Jane','Brown','Digging','8 Parade Rd'], ['id','name','surname','address'])
   person.insert([3,'Okie','Dokey','7 Ocean Rd'], ['id','name','surname','address'])
   person.insert((4,'Maria','Digging','7 Heaven Ave'), ('id','name','hobby','Address'))
   person.insert((5,'Bing','Digging',None), ('id','name','hobby','Address'))
    
   # let's map column ID, FirstName, LastName, Address in database to bintang's Person table.
   columns = {'ID':'id', 'FirstName':'name', 'LastName':'surname', 'Address':'address'}
   # connect to database
   conn = pyodbc.connect("DRIVER={ODBC Driver 17 for SQL Server};SERVER=localhost;PORT=1443;DATABASE=test;Trusted_Connection=yes;")  
   # send data to sql
   ret = person.to_sql(conn, 'Person', columns)
   print(f'{ret} record(s) affected.')
   conn.commit()
   conn.close()


--------------------------
Other Functions/attributes
--------------------------


Bintang.add_table(table_object)
-------------------------------

Add a table to Bintang object. Think Bintang is a container of tables.

:table_object: table object is a table created from create_table function.



Bintang.copy_table(source_tablename, destination_tablename)
-----------------------------------------------------------

Copy a table

:source_tablename: an existing table name from which copy will be made
:destination_tablename: a new table name as the result of the copy



Bintang.create_table(name, columns=None)
----------------------------------------

Create a table inside Bintang object

:name: string to name the table
:columns: a list of columns. Bintang can create columns during record insertion (dynamic schema effect).



Bintang.drop_table(name)
------------------------

Drop table from tables container.

:name: table name

.. code-block:: python
   
   bt.drop_table(name)


Bintang.get_table(name)
-----------------------
Return a table object from Bintang object.

:name: table name

.. code-block:: python

   # assume bt is a Bintang object
   p = bt.get_table('Person') # get Person table object
   print(p) # print Person table object
   # {  
   #   "name": "Person",  
   #   "columns": [
   #       {"id": 0,"name": "id"},  
   #       {"id": 1,"name": "name"},  
   #       {"id": 2,"name": "age"},  
   #       etc...
   # }


Bintang.get_tables()
--------------------
return a list of table's name.

.. code-block:: python

   # assume bt is a Bintang object
   tables = bt.get_tables()



Bintang.name
------------

To rename Bintang object name can be done through normal assignment.

.. code-block:: python
   
   import bintang
   bt = bintang.Bintang('my db')
   bt.name = 'your db' # change name from 'my db' to 'your db'



Bintang.Table.add_column(name)
------------------------------

Add a new column to table. 
Note that intang can also create columns during record insertion (dynamic schema effect).

:column: a string of column name



Bintang.Table.delete(where)
---------------------------

To delete row(s) that meets where conditions.

:where: a lambda expression

.. code-block:: python
   
   # assume p is a Person table
   p.delete(lambda row: row['name'].lower()=='john')

Notes: lambda is case-sensitive.



Bintang.Table.delete_row(index)
-------------------------------

To delete the row at index.

:index: row index



Bintang.Table.drop_column(name)
---------------------------------

Drop a column from a table.

:column: a string of column name


Bintang.Table.get_columns()
---------------------------

Return a list of columns.



Bintang.Table.get_row(index, columns=None, row_type='dict')
-----------------------------------------------------------

Return a row at given index.

:index: row index.
:columns: a list of specific columns wanted in the row.
:row_type: row can be in a 'list' or 'dict' (default)



Bintang.Table.index_exists(index)
---------------------------------

Return True if index exists otherwise None.

:index: row index.



Bintang.Table.name
------------------

To rename table name, can be done through normal assignment.

.. code-block:: python
   
   bt['my table'].name = 'your table' # change name from 'my table' to 'your table'



Bintang.Table.print(columns=None, show_data_type=False)
-------------------------------------------------------

Print rows to terminal in table format. This would be handy if the table can fit into terminal.

:columns: a list of columns to output. If None, will output all columns (default).
:show_data_type: if True, will output data type.

.. code-block:: python

   # assume Person table object exists and has data
   Person.print()



Bintang.Table.rename_column(old_column, new_column)
---------------------------------------------------

Rename column name.

:old_column: the existing column that will be renamed.
:new_column: new column name.



Bintang.Table.update(column, value, where=None)
-----------------------------------------------

To update row(s) in the table

:column: column to be updated. If column does not exist then it will be created (dynamic schema effect).
:value: the value to be set for the row(s). Can also use lambda.
:where: condition in lambda so which row(s) that needs update.

.. code-block:: python

   # assume Person table object exists and has records.
   Person.update('job', 'fisherman') # this will create job column and set value of the rows to 'fisherman'

   # update only row that has name 'John'
   Person.update('job', 'fisherman', where=lambda row: row['name']=='John')

   # create 'full name' column and populate value with name and surname combined.
   bt['Person'].update('full name', lambda row: row['name'] + ' ' + row['surname'])

   # one liner conditional expression is common with lambda.
   # for instance, if you know there is None in surname then you want to resolve the full name as name.
   bt['Person'].update('full name', lambda row: row['name'] if row['surname'] is None else row['name'] + ' ' + row['surname'])



Bintang.Table.update_column(name, data_type=None, column_size=None, ordinal_position=None)
------------------------------------------------------------------------------------------

To update column's attributes, eg. data_type, column_size and ordinal_position.

:name: the column name
:data_type: python data type eg. str, int, float
:column_size: string length if data_type is a str
:ordinal_position: integer for column order.

Note: At the moment data_type and column_size are used for generating sql table and not used for presenting the data.



Bintang.Table.update_row(index, column, value)
----------------------------------------------

To update the row at idx. So only one row will be affected.

:index: row index
:column: which column will be updated
:value: new value



-----------------
Special Functions
-----------------

These functions below create linked tables that read data directly from the source only when needed. 
Therefore these tables do not hold any data in memory and adding/deleting column or records are not allowed.

.. _create_csv_linked_table:

Bintang.create_csv_linked_table(name, filepath, delimiter=',', quotechar='"', header_row=1)
-------------------------------------------------------------------------------------------

Store csv file path and csv attributes when the function gets called. It'll read the data directly from the csv file later only when needed. 
This function will not create in memory table therefore adding/delete column or records are not allowed.
This table is suitable for extracting 'big' data from a csv file that is beyond memory capacity and upload it to a SQL database.
Use read_csv_ function if data manipulation is required.

This function requires pyodbc or psycopg (postgresql specific) connection, therefore you must install the required package.
Below is an example to install the package from a terminal.

Read csv file and populate its records to table.

:name: linked table name to be created
:filepath: a csv file path to read from.
:delimiter: field seperator, by default it'll accept a comma character.
:quotechar: a character to quote the data
:header_row: the row number that contains column name or label.

.. code-block:: python

   from bintang import Bintang
   bt = Bintang()
   bt.create_csv_linked_table('Person', '/path/to/file.csv') 
   ## upload to sql database
   # ... <define sql connection here> ...
   bt['Person'].to_sql(conn, 'PersonTableInSQL')


.. _create_sql_linked_table:

Bintang.create_sql_linked_table(name, conn, sql_str=None, params=None)
----------------------------------------------------------------------

Store sql connection and sql table/statement. It'll read the data directly from the sql database later only when needed. 
This function will not create in memory table therefore adding/delete column or records are not allowed.
This table is suitable for extracting 'big' data from a DB that is beyond memory capacity and dump it to a flat file like csv.
Use read_sql_ function if data manipulation is required.

This function requires pyodbc or psycopg (postgresql specific) connection, therefore you must install the required package.
Below is an example to install the package from a terminal.


.. code-block:: console

   C:\project_dir>pip install pyodbc
   C:\project_dir>pip install psycopg

:name: linked table name to be created
:conn: pyodbc database connection
:sql_str: sql query, if none it will select * from table_name, assuming the table name exists in the database.
:params: sql parameters

.. code-block:: python

   import bintang
   import pyodbc
   
   # connect to sql server
   conn_str = "DRIVER={ODBC Driver 17 for SQL Server};SERVER=localhost;PORT=1443;DATABASE=test;Trusted_Connection=yes;"
   conn = pyodbc.connect(conn_str)
   sql_str = "SELECT * FROM Person WHERE LastName=?"
   params = ('Dokey')

   bt = bintang.Bintang()
   bt.create_linked_table('Person', conn, sql_str, params=params)

   for idx, row in bt['Person'].iterrows():
       print(idx, row)
       # would print
       # 1 {'ID': 3, 'FirstName': 'Okie', 'LastName': 'Dokey', 'address': '7 Ocean Rd'}
       # ...
       # if you want to return your own index/rownum, pass that column to iterrows' rowid parameter, for eg. rowid='yourRownumCol'
       # please note that this will only work for sql data source.

   conn.close()