Question

I have the following query:

UPDATE #Temp_SessionItem SET [Status] = 
    CASE
        WHEN ([AddressFK] IS NULL OR [StatusFK] IS NULL) AND [Status] = 1
            THEN 3
        WHEN [AddressFK] IS NOT NULL AND [StatusFK] IS NOT NULL AND [Status] = 1
            THEN 2
    END

The problem is that when it’s executed it doesn’t actually give me the result I am expecting. i.e. it doesn’t set the value of [Status] field to 3 in case [AddressFK] or [StatusFK] is NULL. Instead, it just tries to add NULL to Status when it should add 3.

If I remove the AND [Status] = 1 part of the expression it does return 3 but then it updates also the values that are not [Status] = 1.

Is there anything obvious that I’m missing here?

I’m using SQL Server 2008.

EDIT:

After Royi Namir pointed out to me I realized that the problem must be further down the stored procedure that this query is being executed in. Specifically, #Temp_SessionItem is just a temporary table. After the upper mentioned query I’m trying to update the original table with the following query:

--  update the status of the original session item table
    UPDATE UploadSessionItem SET [Status] = T.[Status]
    FROM #Temp_SessionItem AS T
    WHERE UploadSessionItem.UploadSessionItemId  = T.ID

..which is obviously not working since all the [Status] items there are still 1

Answer 1

If you only want to affect rows with a current STATUS of 1, you need a WHERE clause:

UPDATE #Temp_SessionItem SET [Status] = 
    CASE
        WHEN ([AddressFK] IS NULL OR [StatusFK] IS NULL)
            THEN 3
        WHEN [AddressFK] IS NOT NULL AND [StatusFK] IS NOT NULL
            THEN 2
    END
WHERE [Status] = 1

---

The update you’ve shown works fine:

create table UploadSessionItem(UploadSessionItemID int,Status int)
insert into UploadSessionItem
select 1,1 union all select 2,2
create table #Temp_SessionItem (ID int,Status int)
insert into #Temp_SessionItem select 1,4
--Your UPDATE:
UPDATE UploadSessionItem SET [Status] = T.[Status]
    FROM #Temp_SessionItem AS T
    WHERE UploadSessionItem.UploadSessionItemId  = T.ID
--
select * from UploadSessionItem

Result:

UploadSessionItemID Status
1                   4
2                   2

So if the problem is elsewhere, it’s not in a code sample you’ve shown us yet.