SQL Basics

SQL Functions

SQL Joins

SQL Advanced

SQL Database

SQL Tables

SQL Constraints

SQL Performance

SQL Data Types

SQL Security

SQL EXISTS Operator

❮ Previous Next ❯

The SQL EXISTS Operator

The EXISTS operator is used to test for the existence of any record in a subquery.

The EXISTS operator returns true if the subquery returns one or more records. Otherwise, it returns false.

EXISTS Syntax

SELECT column_name(s)
FROM table_name
WHERE EXISTS (SELECT column_name FROM table_name WHERE condition);

Demo Database

Customers Table:

CustomerID CustomerName
1 Alfreds Futterkiste
2 Ana Trujillo Emparedados
4 Around the Horn

Orders Table:

OrderID CustomerID
10308 2
10310 1

EXISTS Example

The EXISTS operator can be more efficient than a JOIN or IN clause for checking existence, because it can stop processing the subquery as soon as it finds the first matching row.

The following SQL statement returns TRUE and lists the customer names if they have placed an order:

EXISTS Example

SELECT CustomerName
FROM Customers
WHERE EXISTS (SELECT OrderID FROM Orders WHERE Orders.CustomerID = Customers.CustomerID);

The result set would be:

CustomerName
Alfreds Futterkiste
Ana Trujillo Emparedados

Customer "Around the Horn" would not be listed because they have not placed any orders.

❮ Previous Next ❯