SQL EXISTS Keyword

EXISTS

The EXISTS command tests for the existence of any record in a subquery, and returns true if the subquery returns one or more records.

The following SQL lists the suppliers with a product price less than 20:

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

The following SQL lists the suppliers with a product price equal to 22:

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