A subquery is an inquiry inside another question where a query is characterized to recover information or data again from the database. In a subquery, the external question is called as the main query through the inner query is called subquery. Subqueries are constantly executed first and the consequence of the subquery is passed on to the principal inquiry. It very well may be settled inside a SELECT, UPDATE or some other question. A subquery can likewise utilize any correlation administrators, for example, >,< or =.