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SELECT * FROM EMPLOYEES
WHERE MANAGER_ID IS NULL ;
SELECT *
FROM Employee
WHERE email IS NOT NULL;
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# IS NULL
SELECT column_names FROM table_name WHERE column_name IS NULL;
# IS NOT NULL
SELECT column_names FROM table_name WHERE column_name IS NOT NULL;
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Tests for empty (NULL) values.
Example: Returns users that haven’t given a contact number.
SELECT * FROM users
WHERE contact_number IS NULL;
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SELECT ProductName, UnitPrice * (UnitsInStock + UnitsOnOrder)
FROM Products;