Posts in: Subqueries

Subqueries

Understand what subqueries are and how they allow embedding queries inside other queries to provide powerful, modular logic.

Learn how scalar and row subqueries can return single values or entire rows to be used within SQL queries.

Understand correlated subqueries, which depend on the outer query for their values and are re-executed for each row.

Use IN, EXISTS, ANY, and ALL to test subquery results in WHERE clauses and optimize logic based on result set evaluations.

Understand how to use subqueries inside SELECT, FROM, and WHERE clauses for advanced filtering and data transformation.