Question

我们的查询速度很慢：

select id
from task t 
inner join TaskLog tl 
on t.id = tl.id
where tl.PostImage = 
( 
    select top 1 tll.PostImage 
    from TaskLog tll 
    where tll.id = t.id     
)
group by t1.PostImage, t.id

看起来tl.PostImage =（子查询）导致缓慢。如何重写它以使其运行得更快？

编辑：

我以不正确的方式简化了问题。因此，解决方案对我没有帮助。这是我的实际查询：

SELECT  distinct(p.Task_id), 1 as TotalReferrals
FROM    Task p inner join Task_Log PL on PL.Task_ID = P.Task_ID  
where  (MONTH(P.CreateDate) = @Month
AND     YEAR(P.CreateDate) = @Year)

and  (((p.Worker like 'k3%'
and     p.CreateDate  < '12/6/2010')

or     (p.Worker  in ('k22', 'k27', 'k29')
and     p.CreateDate >= '12/6/2010' and p.ModifiedDate < '12/1/2013')

or     (p.Worker in ('K4A', 'K46', 'K48')
and     p.CreateDate >= '12/1/2013'))

or     (pl.post_image = (select top 1 pll.post_image
                         from    Task_log pll
                         where   pll.Task_id = p.Task_id
                         and     pll.pre_image = 'Unknown'
                         and     pll.changed_column_nm = 'Worker'
                         and    (Month(pll.CreateDate) = @Month
                         and     Year(pll.CreateDate) = @Year)
                         and   ((pll.post_image like 'k3%'
                         and     pll.CreateDate < '12/6/2010')
                          or    (pll.post_image in ('k22', 'k27', 'k29')
                         and     pll.CreateDate >= '12/6/2010' and pll.CreateDate < '12/1/2013')
                         or     (pll.post_image in ('K4A', 'K46', 'K48')
                         and     pll.CreateDate >= '12/1/2013'))
                         group by pll.post_image, pll.log_id
                        )
       ))
group by pl.post_image, p.Task_id, pl.CreateDate

Answer 1

SELECT Min(T.id)
FROM Task T
INNER JOIN TaskLog TL 
ON T.id = TL.id
GROUP BY TL.PostImage

Answer 2

您可能会尝试删除子选择：

SELECT  Distinct(P.Task_id), 1 as TotalReferrals
FROM    Task P
INNER JOIN
        Task_Log PL
ON      PL.Task_ID = P.Task_ID  
WHERE  (MONTH(P.CreateDate) = @Month
AND     YEAR(P.CreateDate) = @Year)

AND  (((P.Worker like 'k3%'
AND     P.CreateDate  < '12/6/2010')

OR     (P.Worker  in ('k22', 'k27', 'k29')
AND     P.CreateDate >= '12/6/2010' and P.ModifiedDate < '12/1/2013')

OR     (P.Worker in ('K4A', 'K46', 'K48')
AND     P.CreateDate >= '12/1/2013'))

OR     (PL.pre_image = 'Unknown'
AND     PL.changed_column_nm = 'Worker'
AND     Month(PL.CreateDate) = @Month
AND     Year(PL.CreateDate) = @Year
AND    (PL.post_image like 'k3%'
AND     PL.CreateDate < '12/6/2010')
OR     (PL.post_image in ('k22', 'k27', 'k29')
AND     PL.CreateDate >= '12/6/2010' 
AND     PL.CreateDate < '12/1/2013')
OR     (PL.post_image in ('K4A', 'K46', 'K48')
AND     PL.CreateDate >= '12/1/2013'))
GROUP BY PL.post_image, P.Task_id, PL.CreateDate

tsql where子句从子查询的前1个值中查找值

2 个答案: