mysql - 多次更新查询mysql

Question

我有一个表，其中主键是两列的组合。我想根据我的主键更新多行

StationId   ServerDate          Status
1           2011-05-05 01:00:00 0
1           2011-05-06 01:00:00 1
2           2011-05-05 01:00:00 2

我的更新查询目前看起来像

Update data set status = 1 where StationId = '1' and  ServerDate = '2011-05-05 01:00:00'
Update data set status = 2 where StationId = '1' and  ServerDate = '2011-05-06 01:00:00'

我正在考虑使用 CASE声明，但不知道当键是两个键的组合时如何使用它。这是我使用 CASE 编写的查询.它改变了我所有的行。如果当前记录不符合记录 3 之类的任何 when 条件，则其更改为默认值 0。我希望该记录保留以前的值。

UPDATE data set status = CASE 
   WHEN StationId = '1' and  ServerDate = '2011-05-05 01:00:00' THEN 1 
   WHEN StationId = '1' and  ServerDate = '2011-05-06 01:00:00' THEN 2 
END 

Answer 1

This is the query I wrote using CASE but I got errors in query

把END关键字后面的“CASE”去掉就可以了:

UPDATE data 
   SET status = 
     CASE 
       WHEN stationId = '1' and ServerDate = '2011-05-05 01:00:00' THEN 1 
       WHEN stationId = '1' and ServerDate = '2011-05-06 01:00:00' THEN 2 
       WHEN stationId = '2' and ServerDate = '2011-05-05 01:00:00' THEN 3
     END
WHERE stationId IN ('1', '2')
  AND ServerDate in ('2011-05-05 01:00:00', '2011-05-06 01:00:00')