使用不同表上的查询过滤查询结果
此查询选择不在 Supervisors 表上的所有员工。
SELECT *
FROM Employees
WHERE EmployeeID not in (SELECT EmployeeID
FROM Supervisors)
使用 LEFT JOIN 可以获得相同的结果。
SELECT *
FROM Employees AS e
LEFT JOIN Supervisors AS s ON s.EmployeeID=e.EmployeeID
WHERE s.EmployeeID is NULL