Question

I don’t quite understand the difference between these three and I see SQLite and PostgreSQL within the SQLAlchemy – so are they a part of SQLAlchemy. Please clarify the differences and the relationships that these database systems may or may not share.

Also, I’m building my app on Heroku – does Heroku support all three of them?

Answer 1

PostgreSQL and SQLite are two relation databases, SQLAlchemy is an ORM which gives you a set of tools for accessing the data in the database.

SQLAlchemy is the Python SQL toolkit and Object Relational Mapper that
gives application developers the full power and flexibility of SQL.

It provides a full suite of well known enterprise-level persistence
patterns, designed for efficient and high-performing database access,
adapted into a simple and Pythonic domain language.

So basically SQLAlchemy gives you the tools to access SQL databases such as PostgreSQL and SQLite Mysql etc, and query them in a pythonic way.

There is this good link on the internet to find out the difference between PostgreSQL and SQLite.

Install PostgreSQL first; then to get started i would look at the tutorials on the SQLAlchemy website, which explains all the terminology you will need to get started.
SQLAlchemy tutorials

These explain simply how to connect to a database, setup SQLAlchemy and how everything pieces together.

It also teaches you how to create tables, using the alchemy code, and how to query datasets.