Illustrate briefly the term SQL sub query

Question

Illustrate briefly the term SQL sub query?

Answer 1

The SQL sub query is a means of querying two or more than two tables at the same time. The sub query itself is an SQL SELECT statement existed in the WHERE clause of another SQL SELECT statement, and separated through being enclosed in parenthesis. Several sub queries have equivalent SQL join structures; however correlated sub queries can’t be duplicated by a join.