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Using a non-correlated subquery in the FROM clause

To help you better understand how to use a non-correlated subquery in the FROM clause, execute the following query:

USE lahmansbaseballdb; SELECT ROUND(AVG(average_salary), 0) AS average_of_all_teams_salariesFROM (SELECT AVG(salary) average_salary FROM salaries GROUP BY teamid);

The preceding query will give you the following error:

Error Code: 1248. Every derived table must have an alias. 

This means that we need to add an alias to the inner query contained in the FROM clause. The subquery used in a FROM clause is also referred to as a derived table. The following highlighted code shows you a proper derived table, along with its alias:

Subquery and derived table terminology are often ...