SQL EXISTS (original) (raw)

Last Updated : 16 Jun, 2026

SQL provides the EXISTS operator to check whether a subquery returns at least one row. It is useful for filtering data based on the presence of related records.

• It checks if a subquery returns one or more rows.
• It returns TRUE if data exists, otherwise FALSE.
• It is commonly used with subqueries.

**Example: First, we create a demo SQL database and tables, on which we use the EXISTS command.

Customers Table

Orders Table

**Query:

SELECT Name
FROM Customers c
WHERE EXISTS (
SELECT 1
FROM Orders o
WHERE o.CustomerID = c.CustomerID
);

**Output:

Output

**Syntax:

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

• **EXISTS: The boolean operator that checks if a subquery returns rows.
• **Subquery: A nested SELECT query that returns data for evaluation.
• **Condition: The condition applied to the subquery.

Examples of SQL EXISTS

Consider the following two relation "Customers" and "Orders".

Customers Table

Orders Table

Example 1 : Using EXISTS with SELECT

To fetch the customers whose website is shared by at least one other customer in the same Customers table.

**Query:

SELECT c1.*
FROM Customers c1
WHERE EXISTS (
SELECT 1
FROM Customers c2
WHERE c2.website = c1.website
AND c2.customer_id <> c1.customer_id
);

**Output:

Output after using EXIST with SELECT

Example 2 : Using NOT with EXISTS

Fetch last and first name of the customers who have not placed any order.

SELECT c.lname, c.fname
FROM Customers c
WHERE NOT EXISTS (
SELECT 1
FROM Orders o
WHERE o.CustomerID = c.customer_id
);

**Output:

Output after using EXIST with NOT

Example 3 : Using EXISTS Condition with DELETE Statement

Delete record of all the customer from Order Table whose website is 'abc.com'.

DELETE FROM Orders
WHERE EXISTS (
SELECT 1
FROM Customers c
WHERE c.customer_id = Orders.CustomerID
AND c.website = 'abc.com'
);

SELECT * FROM Orders;

**Output:

Output after Using EXISTS Condition with DELETE Statement

Example 4 : Using EXISTS Condition with UPDATE Statement

Update the lname as 'Martin' of customer in Customer Table whose customer_id is 401.

UPDATE Customers
SET lname = 'Martin'
WHERE EXISTS (
SELECT 1
FROM Customers c2
WHERE c2.customer_id = 401
AND c2.customer_id = Customers.customer_id
);

SELECT * FROM Customers;

**Output:

Output after using EXIST with UPDATE

To better understand row filtering techniques, see our detailed comparison of EXISTS vs IN in SQL