内联和分部的使用

SELECT *
FROM Staff INNER JOIN
          (SELECT Staff.SPtID AS id, AVG(Staff.salary) AS Expr1
         FROM Staff INNER JOIN
               DPt ON DPt.ID = Staff.SPtID
         GROUP BY Staff.SPtID
         HAVING (AVG(Staff.salary) > 3000)) a ON Staff.SPtID = a.id