Topic 12718 min readStructured Tutorial
SQL Server Single Row Subqueries
Quick Answer
Single row subqueries in SQL Server return exactly one row and one column. They are used in WHERE or HAVING clauses to compare a value against a single result from another query, enabling more dynamic and precise filtering.
Learning Objectives
- Understand what single row subqueries are and when to use them.
- Write SQL Server queries using single row subqueries in WHERE clauses.
- Identify errors caused by subqueries returning multiple rows and how to fix them.
Introduction
In SQL Server, subqueries allow you to embed one query inside another. Single row subqueries are a specific type that return exactly one row and one column.
They are useful when you want to compare a value in your main query against a single value derived from another table or query.
A subquery is a query within a query.
