W3. SQL Exists

Question 1

Q: What does the SQL EXISTS operator do?

Answer 1

A: It tests for the existence of any record in a subquery, returning TRUE if one or more records are found.

Question 2

Q: When does the EXISTS operator return TRUE?

Answer 2

A: When the subquery returns one or more records.

Question 3

Q: Write the syntax for using EXISTS.

Answer 3

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

Question 4

Q: Write a query to list suppliers with a product price less than 20 using EXISTS.

Answer 4

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

Question 5

Q: Write a query to list suppliers with a product price equal to 22 using EXISTS.

Answer 5

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