EXISTS

The SQL EXISTS command verifies if any records exist in a subquery, returning true if the subquery yields one or more records. In the example SQL below, it lists suppliers with a product price below 20.

Example

SELECT SupplierName
FROM Suppliers
WHERE EXISTS (SELECT ProductName FROM Products WHERE SupplierId = Suppliers.supplierId AND Price < 20);

The SQL below retrieves suppliers where the product price equals 22.

Example

SELECT SupplierName
FROM Suppliers
WHERE EXISTS (SELECT ProductName FROM Products WHERE SupplierId = Suppliers.supplierId AND Price = 22);