sql-server - Sql Server JOIN、MAX 和 GROUP BY

Question

我试着拉这个，我有点卡住了。

select 
distinct( msc.id),
 msc.campaignname ,
    max(mst.createdate) as mydate 
from MainMiniSiteCampaign as msc

right join MainMiniSiteTable as mst
on  mst.campaignid = msc.id

order by msc.id
group by msc.id

任何想法我做错了什么？

（错误是“关键字'group'附近的语法不正确）

Answer 1

GROUP BY需要在之前ORDER BY

编辑：我没有读那么远:)

因为无论如何你都在分组，所以你根本不需要distinct。

select 
msc.id,
 msc.campaignname ,
    max(mst.createdate) as mydate 
from MainMiniSiteCampaign as msc

right join MainMiniSiteTable as mst
on  mst.campaignid = msc.id

group by msc.id, msc.campaignname

而且由于 group by 在 MySQL 中意味着 order by，因此您无需指定ORDER BY两者。但是您可能希望在组中添加活动名称，否则将选择每个 msc.id 组的随机活动名称。或者在不需要时将其从选择中删除。

Answer 2

首先你应该写 group by 然后 order by ：

按 msc.id 分组
按 msc.id 订购

Answer 3

select 
msc.id,
min( msc.campaignname) ,
max(mst.createdate) as mydate 

from MainMiniSiteCampaign as msc
right join MainMiniSiteTable as mst on  mst.campaignid = msc.id

group by msc.id
order by msc.id

distinct(msc.id)使用时不需要group by msc.id

Answer 4

像这样试试

select 
distinct( msc.id),
msc.campaignname ,
max(mst.createdate) as mydate 
from MainMiniSiteCampaign as msc

right join MainMiniSiteTable as mst
on  mst.campaignid = msc.id

group by msc.id
order by msc.id