Question

如何重做以下查询以仅使用JOIN而不是嵌套查询？

SELECT SUM(allqty) AS allqty
    ,COUNT(*) AS orders 
FROM (SELECT SUM(S.Qty) AS allqty
      FROM data_intra.yw1_ordersheet S
      INNER  JOIN data_intra.productdata P ON P.productid=S.productid
      WHERE P.eCode LIKE (SELECT eCode
                          FROM data_intra.productdata
                          WHERE productid=1001)
      GROUP BY S.OrderPO) as A;

Answer 1

这是2个猜测。两者都使用IN（）而不是LIKE（）

这将为每个S.OrderPO

生成一行

SELECT
      SUM(S.Qty) AS allqty
    , S.OrderPO
FROM data_intra.yw1_ordersheet S
      INNER JOIN data_intra.productdata P
                  ON P.productid = S.productid
WHERE P.eCode IN (
            SELECT
                  eCode
            FROM data_intra.productdata
            WHERE productid = 1001
      )
GROUP BY
      S.OrderPO
;

这将产生一行，计算S.OrderPO的不同数量

SELECT
      SUM(S.Qty)                AS allqty
    , COUNT(DISTINCT S.OrderPO) AS orders
FROM data_intra.yw1_ordersheet S
      INNER JOIN data_intra.productdata P
                  ON P.productid = S.productid
WHERE P.eCode IN (
            SELECT
                  eCode
            FROM data_intra.productdata
            WHERE productid = 1001
      )
;

重新安排MySQL嵌套查询

1 个答案: