Play around with PostgreSQL with docker so that you don't have to install it locally and can throw it away.
Install PostgreSQL client/server in Ubuntu 18.04.
A buildup of how to generate a query to create a "leaderboard" of of your top scorers.
Calculate the distance between two points on earth using PostGIS.
Import spatial data into PostgreSQL and query the data with the help of PostGIS.
Install PostGIS in PostgreSQL.
Install the routing extension for PostgreSQL
Learn how to use UUIDs in MySQL for your table IDs, rather than using auto_increment.
How to install PostgreSQL on Ubuntu 16.04
Configure your PostgreSQL database
A cheatsheet for using PostgreSQL