Question

可能重复：
How to combine these two SQL statements?

我有2个SQL查询。它们根据变量等于表中的CMSUID或CASUID值得到计数。否则，他们是完全一样的。如何将它们组合成单个查询，可能使用CASE语句。

select @cntCM_CNF = count(distinct(c.ID_Case))
from dbo.Cases c
join dbo.vew_CasePersonnelSystemIDs vcps on c.ID_Case = vcps.ID_Case
join hearings h on c.ID_Case = h.ID_Case
where vcps.CMSUID = @nSUID
    and h.HearingDate > getdate()
    and h.OnCalendar = 1 and h.Scheduled = 1
    and dbo.fn_HearingConfirmedNoHOs(h.ID_Hearing) < 2

select @cntCC_CNF = count(distinct(c.ID_Case))
from dbo.Cases c
join dbo.vew_CasePersonnelSystemIDs vcps on c.ID_Case = vcps.ID_Case
join hearings h on c.ID_Case = h.ID_Case
where vcps.CASUID = @nSUID
    and h.HearingDate > getdate()
    and h.OnCalendar = 1 and h.Scheduled = 1
    and dbo.fn_HearingConfirmedNoHOs(h.ID_Hearing) < 2

我无法弄清楚如何组合它们，因为结果是不同项目的数量。不知道如何实现这一目标。

Answer 1

是......

select 
    @cntCM_CNF = count(distinct case when vcps.CMSUID = @nSUID then c.ID_Case else null end),
    @cntCC_CNF = count(distinct case when vcps.CASUID = @nSUID then c.ID_Case else null end)
from dbo.Cases c
join dbo.vew_CasePersonnelSystemIDs vcps on c.ID_Case = vcps.ID_Case
join hearings h on c.ID_Case = h.ID_Case
where 
    h.HearingDate > getdate()
    and h.OnCalendar = 1 and h.Scheduled = 1
    and dbo.fn_HearingConfirmedNoHOs(h.ID_Hearing) < 2 AND
    (vcps.CASUID = @nSUID OR vcps.CMSUID = @nSUID) --<<<<added for performance reasons

Answer 2

了解UNION的工作原理。

基本上，您将在一列中选择一个计数，0，然后在另一列中选择0。

您可能需要使用UNION ALL

select @cntCM_CNF = count(distinct(c.ID_Case)) AS Col1, 0 As Col2
from dbo.Cases c
join dbo.vew_CasePersonnelSystemIDs vcps on c.ID_Case = vcps.ID_Case
join hearings h on c.ID_Case = h.ID_Case
where vcps.CMSUID = @nSUID
    and h.HearingDate > getdate()
    and h.OnCalendar = 1 and h.Scheduled = 1
    and dbo.fn_HearingConfirmedNoHOs(h.ID_Hearing) < 2
UNION ALL
select 0 as Col1, @cntCC_CNF = count(distinct(c.ID_Case)) AS Col2
from dbo.Cases c
join dbo.vew_CasePersonnelSystemIDs vcps on c.ID_Case = vcps.ID_Case
join hearings h on c.ID_Case = h.ID_Case
where vcps.CASUID = @nSUID
    and h.HearingDate > getdate()
    and h.OnCalendar = 1 and h.Scheduled = 1
    and dbo.fn_HearingConfirmedNoHOs(h.ID_Hearing) < 2

如何将这两个SELECT组合成一个？

2 个答案: