Conditional Expression - i.e., IIF in Access

I have a query with a conditional expression that I can do just fine in Access but I am having a bear of a time trying to create a similar SQL View. Baiscally I want to say, if column A is null, use value B else use value C.

In Access the SQL is this:

SELECT IIf([Categorycode] Is Null,[tblconstituents].[CASNumber],[categorycode]) AS Casnumber, Sum(qryweldingrod3a.CFume) AS CFume, Sum(qryweldingrod3a.cslag) AS cSlag
FROM qryweldingrod3a INNER JOIN tblconstituents ON qryweldingrod3a.CASNumber = tblconstituents.CASNumber
GROUP BY IIf([Categorycode] Is Null,[tblconstituents].[CASNumber],[categorycode]);

But I know you can't use the IIF statement in SQL so I was trying CASE and was still coming up empty handed. Here is what I produced in SQL but it didn't work:

SELECT SUM(dbo.RecycleWR_qryWeldingRod3a_LBS.CFume) AS CFume, SUM(dbo.RecycleWR_qryWeldingRod3a_LBS.CSlag) AS cSlag,

CASNumber = CASE Type
WHEN categoryCode IS NULL THEN dbo.tblConstituents.CASNumber ELSE CategoryCode
END,
FROM dbo.tblConstituents INNER JOIN
dbo.RecycleWR_qryWeldingRod3a_LBS ON dbo.tblConstituents.CASNumber = dbo.RecycleWR_qryWeldingRod3a_LBS.CASNumber
GROUP BY dbo.RecycleWR_qryWeldingRod3a_LBS.CASNumber

Any ideas would be greatly appreciated.SELECT CASE WHEN ColA IS NULL THEN ColB ELSE ColC END|||Originally posted by Brett Kaiser
SELECT CASE WHEN ColA IS NULL THEN ColB ELSE ColC END

Well, when I do that, I get
"The Query Designer does not support the CASE SQL construct."

Can you even use CASE in a view?|||Also, I need to assign an alias to that column.|||What are you using?

Aren't you using query analyzer?

If you're using Access you may need to make it a PASS THRU query

SELECT CASE WHEN ColA IS NULL THEN ColB ELSE ColC END AS NewCol|||I was creating the query in VIEW but I got around it using a function. Took me awhile but its working fine now. Thanks for your help|||What do you mean in VIEW?

Are you doing this in Enterprise Manager?

I would recommend against that.|||Wether you use the designer in access or in EM, you'll loose the graphical representation of your query when you use CASE (and a bunch of other constructs). This is what the error message says. The query should run fine, anyway and you should see and be able to modify the sql source in access.
However, beware of the designer, especially if you have complex where clauses. All sorts of weird things may happen to your sql ;)|||What s/he said...

Use QA though for SQL Server development...

You'll have a lot less headaches...