Question

好的：这是我的一些表结构，这里很重要

CaseStudyID int
Title nvarchar(50)
OverrideTitle nvarchar(50)

我的部分程序

Declare @Temp table(CaseStudyID int,
            Title nvarchar(50))

Insert Into @Temp 
SELECT CaseStudyID,Title 
FROM CaseStudy 
WHERE Visible = 1 AND DisplayOnHomePage = 1 
ORDER BY Title

Update @Temp Set Title = TitleOverride 
--Here is where im lost if the title occurs more than once
--I need to replace it with the override
--Schoolboy error or leaking brain I cant get it going


Select * From @Temp

有人可以帮忙吗？

Answer 1

我不确定你是否需要原始表的每一行。所以这是我的替代解决方案，为您提供每一行：

SELECT CaseStudyID, Title 
FROM CaseStudy c1
WHERE NOT EXISTS (
   SELECT * FROM CaseStudy c2 
   WHERE c2.CaseStudyID <> c1.CaseStudyID and c2.Title = c1.Title
)

UNION ALL

SELECT CaseStudyID, OverrideTitle
FROM CaseStudy c1
WHERE exists (
   SELECT * FROM CaseStudy c2
   WHERE c2.CaseStudyID <> c1.CaseStudyID and c2.Title = c1.Title
)

ORDER BY Title

Answer 2

你可以在不使用临时表的情况下实现它：

SELECT 
    MIN(CaseStudyID) AS CaseStudyID, 
    CASE WHEN count(*) = 1 THEN 
       MIN(Title) 
    ELSE
       MIN(OverrideTitle) 
    END AS Title
FROM CaseStudy
GROUP BY Title
ORDER BY Title

Answer 3

这将替换使用相应的overrideTitle值多次出现的每个标题。

它将保留第一次出现，例如，如果您有3个标题，如a，a，a只有第二个，第三个将被替换

select distinct
    cs1.CaseStudyID,
    case when cs2.CaseStudyID is null then cs1.Title else cs1.overrideTitle end as title
from  
    CaseStudy cs1
    left join CaseStudy cs2 
        on cs1.title = cs2.title
        and cs1.CaseStudyID > cs2.CaseStudyID

如果您想要替换所有这些，只需更改＆gt;到＆lt;＆gt;如下

select distinct
    cs1.CaseStudyID,
    case when cs2.CaseStudyID is null then cs1.Title else cs1.overrideTitle end as title
from  
    CaseStudy cs1
    left join CaseStudy cs2 
        on cs1.title = cs2.title
        and cs1.CaseStudyID <> cs2.CaseStudyID

在T-SQL中混淆了聚合

3 个答案: