Case when over partition

Question

Hi,
I have the following logic below that doesn't work as I would have hoped/expected.

Here's the statement:

Select
Apps.name,
substring(apps.code,3,7),

Max(case when comp.id = 1 and comp.val = 1 then comp.desc else substring(apps.code,3,7) end) over (partition by substring(apps.code,3,7)) as cust_id

From
Dbo.apps
Left join dbo.comps
On apps.id = comps.id

The reason that it doesn't work is that I get exactly the same values as the column substring(apps.code,3,7) and I should be expecting a combination of the two.

Is there something wrong with my case statement please?

Answer 1

Hi @Bone_12

I get exactly the same values as the column substring(apps.code,3,7)

With this OVER clause over (partition by substring(apps.code,3,7)), you will always get the same Max Value.
Here is my guess based on your description, if it doesn't work, please provide more details including some sample data and your desired output.

Select Apps.name  
      ,substring(apps.code,3,7)  
      ,Max(case when comp.id = 1 and comp.val = 1 then comp.desc else substring(apps.code,3,7) end)as cust_id  
From Dbo.apps Left join dbo.comps On apps.id = comps.id  
Group by Apps.name,substring(apps.code,3,7)  

Best regards,
LiHong

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Answer 2

Is there something wrong with my case statement please?

We can't say, because we don't have your data and we don't know which result you expect.
Please post table design as DDL, some sample data as DML statement and the expected result.