FROM 子句中的子查询

Created: November-22, 2018

FROM 子句中的子查询的行为类似于在执行查询期间生成并在之后丢失的临时表。

SELECT Managers.Id, Employees.Salary
FROM (
  SELECT Id
  FROM Employees
  WHERE ManagerId IS NULL
) AS Managers
JOIN Employees ON Managers.Id = Employees.Id