SELECT s.IN1 - s.OUT +s.IN2 FROM (select sum(入库数量) AS IN1 from 表1 select sum(借出数量) AS OUT from 表2 select sum(归还数量) AS IN2 from 表3 ) s
SELECT 表1.productid, SUM(ISNULL(表1.入库数量,0))-SUM(ISNULL(表2.借出数量,0))+SUM(ISNULL(表3.归还数量,0)) FROM 表1 LEFT JOIN 表2 ON 表1.productid=表2.productid LEFT JOIN 表3 ON 表1.productid=表3.productid GROUP BY
2楼发错了SELECT 表1.productid, SUM(ISNULL(表1.入库数量,0))-SUM(ISNULL(表2.借出数量,0))+SUM(ISNULL(表3.归还数量,0)) FROM 表1 LEFT JOIN 表2 ON 表1.productid=表2.productid LEFT JOIN 表3 ON 表1.productid=表3.productid GROUP BY 表1.productid
FROM
(select sum(入库数量) AS IN1
from 表1 select sum(借出数量) AS OUT
from 表2
select sum(归还数量) AS IN2
from 表3
) s
SELECT 表1.productid,
SUM(ISNULL(表1.入库数量,0))-SUM(ISNULL(表2.借出数量,0))+SUM(ISNULL(表3.归还数量,0))
FROM 表1 LEFT JOIN
表2 ON 表1.productid=表2.productid LEFT JOIN
表3 ON 表1.productid=表3.productid
GROUP BY
SUM(ISNULL(表1.入库数量,0))-SUM(ISNULL(表2.借出数量,0))+SUM(ISNULL(表3.归还数量,0))
FROM 表1 LEFT JOIN
表2 ON 表1.productid=表2.productid LEFT JOIN
表3 ON 表1.productid=表3.productid
GROUP BY 表1.productid