列具有多个值，用作下一列的标识符

Question

MySQL列有多个值用作下一列的标识符。表结构：

id (key),  occurrence_id,  name,  value

name列值对应于values列。如何在一个视图中显示此信息？

目前，它看起来像这样：

occurrence_id name           value
1576          Attempts       1
1576          ClientIP       "94.xxx.xxx.xxx"
1576          UserAgent      ""
1576          CurrentUserID  0<

我想制作一个如下所示的视图：

occurrence_id  Attempts  Client IP         CurrentUserID
1576           1         "94.xxx.xxx.xxx"  0
2009           30        "68.111.xxx.xxx"  0

Answer 1

一种方法是使用条件聚合：

select occurrence_id,
       max(case when name = 'Attempts' then value end) as Attempts,
       max(case when name = 'ClientIP' then value end) as ClientIP,
       max(case when name = 'UserAgent' then value end) as UserAgent,
       max(case when name = 'CurrentUserID' then value end) as CurrentUserID
from table t
group by occurrence_id;