mysql - SQL根据条件合并两个表

Question

我有两个 View ，其结果将如下所示获取

select * from CMDowntimes
select * from PMDowntimes

两个 View 的结果均显示在图像中。除最后一列外，所有列名称均相同 对于 q 结果 Ser，最后一个列名称是“CMDownTime”，对于另一个“PMDowntime”

现在我想合并这两个表，如图所示 即，如果两个 View 中都存在相同的 id，则结果中应该是单行，并且两列均为“PM_Downtime”和“CM_DownTime” 如果数据来自单个表[ View ]，则另一个表应为零(如果仅存在 CM_Downtime，则 PM_Downtime 应为零)

等待快速回复 提前致谢

ID Rgn  Ter   StartDate                  EndDate                    CreatedDate  CM_Downtime
13  8   14    2014-10-24 00:30:00.000    2014-10-31 01:00:00.000    2014-10-15   10110
14  6   7     2014-10-01 09:39:00.000    2014-10-03 00:30:00.000    2014-10-26   2331
15  8   14    2014-10-01 09:54:00.000    2014-10-29 09:54:00.000    2014-10-26   40320

ID Rgn  Ter   StartDate                  EndDate                    CreatedDate  PM_Downtime
14  6   7     2014-10-01 09:39:00.000    2014-10-03 00:30:00.000    2014-10-26   2331
16  8   14    2014-10-17 09:57:00.000    2014-10-24 09:57:00.000    2014-10-26   10080


ID Rgn  Ter   StartDate                  EndDate                    CreatedDate  CM_Downtime   PM_Downtime
13  8   14    2014-10-24 00:30:00.000    2014-10-31 01:00:00.000    2014-10-15   10110         0
14  6   7     2014-10-01 09:39:00.000    2014-10-03 00:30:00.000    2014-10-26   2331          2331
15  8   14    2014-10-01 09:54:00.000    2014-10-29 09:54:00.000    2014-10-26   40320         0
16  8   14    2014-10-17 09:57:00.000    2014-10-24 09:57:00.000    2014-10-26   0             10080  

Answer 1

这本质上是一个完全外部连接。您可以在 SQL Server 或 MySQL 中使用带有聚合的 union all 来执行此操作:

select id, rgn, terr, StartDate, EndDate, CreatedDate,
       max(CM_DownTime) as CM_DownTime, max(PM_DownTime) as PM_DownTime
from (select ID, Rgn, Ter, StartDate, EndDate, CreatedDate, CM_Downtime, 0 as PM_DownTime
      from CMDowntimes
      union all
      select ID, Rgn, Ter, StartDate, EndDate, CreatedDate, 0 as CM_Downtime, PM_DownTime
      from PMDownTimes
     ) dt
group by id, rgn, terr, StartDate, EndDate, CreatedDate;

SQL Server 支持完全外连接。在该数据库中，这可能会满足您的要求:

select coalesce(c.id, p.id) as id, coalesce(c.rgn, p.rgn) as rgn, coalesce(c.terr, p.terr) as terr,
       coalesce(c.StartDate, p.StartDate) as StartDate, coalesce(c.EndDate, p.EndDate) as EndDate,
       coalesce(c.CreatedDate, p.CreatedDate) as CreatedDate,
       coalesce(c.CM_Downtime, 0) as CM_Downtime,
       coalesce(p.PM_Downtime, 0) as PM_Downtime
from CMDownTimes c full outer join
     PMDownTimes p
     on c.id = p.id;