Question

我有一个问题，我必须将以下MSSQL转换为MySQL。我有两个主要问题。

＆＃34;＃WU＆＃34;是一个不起作用的临时表。我试着替换它 CREATE TEMPORARY TABLE WU但是没有解释就错了。
我想知道调用多个案例的正确方法。

我已尝试移除MAX，并将其切换为WU1 =（例如，当rk = 1那么结束时），但这不起作用。

代码如下：

SELECT ReqN,
MAX(CASE WHEN rk = 1 THEN WU END) AS WU1,
MAX(CASE WHEN rk = 2 THEN WU END) AS WU2,
MAX(CASE WHEN rk = 3 THEN WU END) AS WU3,
MAX(CASE WHEN rk = 4 THEN WU END) AS WU4,
MAX(CASE WHEN rk = 5 THEN WU END) AS WU5,
MAX(CASE WHEN rk = 6 THEN WU END) AS WU6,
MAX(CASE WHEN rk = 7 THEN WU END) AS WU7,
MAX(CASE WHEN rk = 8 THEN WU END) AS WU8

into #tblWU

FROM (SELECT ReqN, WUnit,
   (SELECT COUNT(*) 
    FROM tblDevWU AS B
    WHERE B.ReqN = A.ReqN
    AND B.WUnit <= A.WUnit) AS rk
    FROM tblDevWU AS A) as A 
    GROUP BY ReqN;

Answer 1

与此等效的Mysql是：

CREATE TEMPORARY TABLE tblWU AS
SELECT ReqN,
MAX(IF(rk=1, WU, NULL)) WU1,
MAX(IF(rk=2, WU, NULL)) WU2,
MAX(IF(rk=3, WU, NULL)) WU3,
MAX(IF(rk=4, WU, NULL)) WU4,
MAX(IF(rk=5, WU, NULL)) WU5,
MAX(IF(rk=6, WU, NULL)) WU6,
MAX(IF(rk=7, WU, NULL)) WU7,
MAX(IF(rk=8, WU, NULL)) WU8
FROM (
   SELECT ReqN, WUnit,
      (
       SELECT COUNT(*) FROM tblDevWU AS B
       WHERE B.ReqN = A.ReqN AND B.WUnit <= A.WUnit
      ) AS rk
   FROM tblDevWU AS A) as A 
GROUP BY ReqN;

选择中有多个案例

1 个答案: