postgresql-interface 0.0.4

Library to load and extract data from a PosgreSQL Database with Python with a simple SQL style language

PostgreSQLInterface

Introduction

This package allows to load and extract data from a PosgreSQL Database using simple SQL style methods. At the moment, it has only been tested on a Heroku Postgres Database, though it should not be hard to extended the init method to be able to interact with other cloud or premises providers that uses PosgresSQL technology (maybe the method create_connection will also need to be modified). Also, It could be used as reference to create new interfaces to connect to other RDBS the same way this one is inspired on the one to connect to SQLServer located on the library berryworld.

Structure

The library has an unique class that handles the relations to a database allowing to load and extract data. Below, you can find a little introduction to all relevant methods. For more information, read the doc of the method or take a look to the tests in the repo.

Instantiate the class

To instantiate the class to connect to a Heroku Database:

heroku_db = PostgreSQL(database_url)

database_url can be found on the section Config Vars inside the tab Settings of your Heroku app or on the section Database Credentials of the tab Settings of your Heroku Datastore.

Read data from Database

To retrieve a query from the database:

my_table = heroku._db.query("SELECT * FROM test.data")

It is also possible to do more complicated queries:

my_table = heroku._db.query("SELECT * FROM test.data d JOIN test.references r ON d.referencesid = r.id")

Insert data

To insert data into a table:

heroku_db.insert_table('test.simple', to_insert.copy())

Update a table

To update data into a table:

heroku_db.update_table('test.simple', to_update, ['id', 'date'])

Delete from table

To delete from a table:

heroku_db.delete_from_table('test.simple', to_delete)

Execute a general statement

To execute a general SQL statement you can use the method execute. This method returns no data. It is important to notice that it is not the SQL execute command. As an example, you can use it to create a schema:

heroku._db.execute("CREATE SCHEMA test")

You can also use it to execute a stored procedure

heroku._db.execute("EXECUTE test.sp_test1 @input = '%s" @ input)

Tests

To be able to execute the tests, it is necessary to provide a '.env' file with the url to connect to a Heroku database.