Follow this step-by-step guide to install PostgreSQL, load data, connect to a database, and execute SQL queries including table joins PostgreSQL is an open-source, object-relational (also called ...

Normalized data giving you problems? Learn how to use the SQL subselect statement and handle your database like a pro! Do you ever find yourself juggling queries to get the information you need?

A common SQL habit is to use SELECT * on a query, because it’s tedious to list all the columns you need. Plus, sometimes those columns may change over time, so why not just do things the easy way? But ...