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SQL Basics in PostgreSQL

Quiz

Instruction

This quiz is too easy for you! OK, let's see how much you remember about various JOINs.

player (id, name, ranking, country)

coach (id, player_id, name, country)

We now have two tables with tennis players and their coaches. Each player can have one or more coaches. Each coach can train one player or can be unemployed.

The columns should be obvious for you.

Exercise

Show all coaches together with the players they train, show all columns for coaches and players. Show unemployed coaches with NULLs instead of player data.

Stuck? Here's a hint!

Use the following template to help you build your query:

SELECT ...
FROM ...
LEFT JOIN ...
  ON ...;