0

这是我的初始查询：

select 
CASE WHEN a.TO_WG_ID is null 
and a.CREATED_DATE_TIME = 
(select min(b.created_date_time) from ymtn.message b 
where b.thread_id = a.thread_id) THEN 1 ELSE 0
END AS "Created"
from ymtn.MESSAGE a 
left join YMTN.WORKGROUP b
ON a.FROM_WG_ID=b.WORKGROUP_ID
where b.WORKGROUP_ID='1STOP_PROCESS'

它给了我一列有一堆 1' 和 0's。我想要的只是总和..只是一个数字，例如 1691。如果我在 case 语句前面放一个 SUM，我会收到此错误： Msg 130, Level 15, State 1, Line 5 Cannot perform a aggregate function on an expression包含聚合或子查询。那么我该怎么做呢？我已经使它与这个查询一起工作：

select count(CREATED_DATE_TIME) as 'Created'
from ymtn.MESSAGE a
LEFT JOIN YMTN.WORKGROUP b
ON a.FROM_WG_ID=b.WORKGROUP_ID
where CREATED_DATE_TIME=(SELECT MIN(b.CREATED_DATE_TIME) FROM YMTN.MESSAGE b WHERE
 b.THREAD_ID = a.THREAD_ID)
and a.TO_WG_ID is null
and b.WORKGROUP_ID='1STOP_PROCESS'

但是，我希望它在 case 语句中工作，而不必将嵌套选择向下移动到 WHERE 子句。

4

1 回答 1

1

你可以把整个事情扔到一个子查询中然后求和吗？

select sum(Created)
from (
    select 
    CASE WHEN a.TO_WG_ID is null 
    and a.CREATED_DATE_TIME = 
    (select min(b.created_date_time) from ymtn.message b 
    where b.thread_id = a.thread_id) THEN 1 ELSE 0
    END AS "Created"
    from ymtn.MESSAGE a 
    left join YMTN.WORKGROUP b
    ON a.FROM_WG_ID=b.WORKGROUP_ID
    where b.WORKGROUP_ID='1STOP_PROCESS'
) a
于 2014-06-19T17:30:48.157 回答