dbpd 1.1

Python module for establishing a working relationship between relational databases and Pandas DataFrames

dbpd

The main theme of this module is to establish a working relationship between relational databases and Pandas DataFrames; because these objects are tabular in nature, it reveals itself to be an efficient way to inspect, manage and manipulate a given database.

The dbpd.BaseDBPD class is the parent class for six child classes that are specific to different database types:

dbpd.Access
dbpd.MySQL
dbpd.Oracle
dbpd.Postgres
dbpd.SQLite
dbpd.SQLiteInMemory

Abstractions have been created such that working with these various database types is consistent throughout the user's code base.

The query() method is responsible for returning SELECT sql statements as their respective DataFrames. However the query() method can also be used to make changes to the database (such as INSERT, UPDATE, DELETE, etc.)

Users are expected to write their own sql statements to query the database, and parameterized queries are accepted and encouraged as well.

This is not meant to be an Object-Relational-Mapper (ORM) and has no such functionality, although it may be possible for users to create their own ORM using the classes herein.

DOCUMENTATION https://zacharybeebe.github.io/dbpd/

Installation

pip install dbpd

Connecting to a Database #1 - Direct

from dbpd import Oracle

oracle = Oracle(
    username='example_username',
    password='example_password',
    host='127.0.0.1',
    sid='prod',
    port=5000,
    threaded=True,
    description='My Example Oracle database',
    show_description=True
)
dataframe = oracle.query('SELECT * FROM example_table')
oracle.close()

Connecting to a Database #2 - Inheritance

from dbpd import Postgres

class ExamplePostgres(Postgres):
    def __init__(self):
        super(ExamplePostgres, self).__init__(
            username='example_username',
            password='example_password',
            host='127.0.0.1',
            database_name='example',
            port=5000,
            postgres_schema='public',
            description='My Example Postgres database',
            show_description=True
        )
    
    def awesome_custom_method(self):
        print('I love pandas and databases')

pg = ExamplePostgres()
dataframe = pg.query('SELECT * FROM public.example_table')
pg.close()

Other Examples

from dbpd import Access, MySQL, SQLite, SQLiteInMemory

# Connect to existing Access Database
existing_access = Access(
    filepath='path/to/existing/access.accdb',
    fernet_encryption_key=b'<theFernetEncryptionKeyForYourDatabase>',
    description='My Existing Access database',
    show_description=True
)
existing_access.close()

#####################################################################
# Create new, blank Access Database
new_access = Access(
    filepath='path/to/non-existent/access.accdb',
    fernet_encryption_key=b'<theFernetEncryptionKeyForYourDatabase>',
    description='My New Access database',
    show_description=True
)
new_access.query(
    sql="""
    CREATE TABLE my_table (
        [a_number]  INTEGER,
        [a_date]    DATETIME,
        [a_double]  DOUBLE,
        [a_string]  VARCHAR
    );
    """
)
new_access.commit()
new_access.insert_values(
    table_name='my_table',
    a_number=1,
    a_date=new_access.dt_now(),
    a_double=22.22,
    a_string='HelloWorld'
)
new_access.commit()
new_access.close()

#####################################################################
# Connect to MySQL Database
mysql = MySQL(
    username='example_username',
    password='example_password',
    host='127.0.0.1',
    database_name='example',
    port=5000
)
# Export query to SQLite database
dataframe = mysql.export_query_to_sqlite(
    out_filepath='path/to/export/sqlite.db',
    out_table_name='exported_table',
    in_sql="""
        SELECT
            A.*,
            B.*
        FROM
            example_table A
        LEFT JOIN (
            SELECT
                *
            FROM
                other_table
        ) B ON A.id = B.id
        WHERE
            A.column = :value
    """,
    in_parameters={'value': 'This value'}      
)
mysql.close()

#####################################################################
# Connect to an Existing SQLite database
existing_sqlite = SQLite(
    filepath='path/to/existing/sqlite.db',
)
existing_sqlite.close()

#####################################################################
# Create a new, blank SQLite database
new_sqlite = SQLite(
    filepath='path/to/non-existent/sqlite.db',
)
new_sqlite.close()

#####################################################################
# Create a new in-memory SQLite database and save to disk
in_mem_sqlite = SQLiteInMemory()
in_mem_sqlite.query(
    sql="""
        CREATE TABLE my_table (
            [a_number]  INTEGER,
            [a_date]    DATETIME,
            [a_double]  DOUBLE,
            [a_string]  VARCHAR
        );
        """
)
in_mem_sqlite.commit()
in_mem_sqlite.insert_values(
    table_name='my_table',
    a_number=1,
    a_date=new_access.dt_now(),
    a_double=22.22,
    a_string='HelloWorld'
)
in_mem_sqlite.commit()
saved_sqlite = in_mem_sqlite.save_as(
    filepath='path/to/sqlite.db',
    return_new_database_manager=True
)
in_mem_sqlite.close()
dataframe = saved_sqlite.query('SELECT * FROM my_table')
saved_sqlite.close()