What is derived table?
Derived tables are SELECT statements in the FROM clause referred to by an alias or a user-specified name. The result set of the SELECT in the FROM clause forms a table used by the outer SELECT statement. For example, this SELECT uses a derived table to find if any store carries all book titles in the pubs database: SELECT ST.stor_id, ST.stor_name FROM stores AS ST, (SELECT stor_id, COUNT(DISTINCT title_id) AS title_count FROM sales GROUP BY stor_id ) AS SA WHERE ST.stor_id = SA.stor_id AND SA.
