SQL Subquery

Last update on August 19 2022 21:50:30 (UTC/GMT +8 hours)

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SQL Subquery

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What is SQL Sqbquery?

A subquery is a SQL query nested inside a larger query.

Where Subquery Occurs?

A subquery may occur in -

A SELECT clause
A FROM clause
A WHERE clause
The subquery can be nested inside a SELECT,INSERT,UPDATE,or DELETE statement or inside another subquery.
A subquery is usually added within the WHERE Clause of another SQL SELECT statement.
You can use the comparison operators, such as >, <, or =.

Subquery Syntax

Type of Subqueries

Single row subquery : Returns zero or one row.
Multiple row subquery : Returns one or more rows.
Multiple column subquery : Returns one or more columns.
Correlated subqueries : Reference one or more columns in the outer SQL statement.
Nested subqueries : Subqueries are placed within another subqueries.