Need help converting a select query into a case statement

I have the following query:

(SELECT MIN(CFGDates.AccountPdEnd)
FROM CFGDates LEFT JOIN
AR ON AR.Period = CFGDates.Period
WHERE AR.Period = '200408')

I need to convert this into a case statement.
I tried various ways but did not get the result that I was after

Thanks,
LauraConvert a SELECT statement into a CASE statement?

I haven't a clue what you are intending to do.|||This is the query that I am dealing with:

SELECT PR.WBS1, PR.Name, AR.InvoiceDate, AR.Invoice AS InvoiceNumber,
CASE WHEN (AR.InvoiceDate = '')
THEN '0'
ELSE DATEDIFF(day, AR.InvoiceDate, ********* need to insert case statement to find the end of the period ************** ) END AS DaysOld,
SUM(CASE WHEN LedgerAR.TransType = 'IN' THEN - 1 * LedgerAR.Amount WHEN LedgerAR.TransType = 'CR' AND
LedgerAR.SubType = 'T' THEN - 1 * LedgerAR.Amount ELSE LedgerAR.Amount END) AS InvoiceBalance,
SUM(CASE WHEN LedgerAR.TransType = 'IN' AND LedgerAR.SubType = 'I' THEN - 1 * LedgerAR.Amount ELSE 0 END) AS Interest,
SUM(CASE WHEN LedgerAR.TransType = 'IN' AND LedgerAR.SubType = 'R' THEN LedgerAR.Amount ELSE 0 END) AS Retainage,
SUM(CASE WHEN (LedgerAR.WBS2 <> '9001' AND AR.Period = '200408') THEN - 1 * LedgerAR.Amount ELSE 0 END) AS total
FROM PR LEFT OUTER JOIN
AR ON AR.WBS1 = PR.WBS1 AND PR.WBS2 = '' AND PR.WBS3 = '' LEFT JOIN
LedgerAR ON AR.WBS1 = LedgerAR.WBS1 AND AR.WBS2 = LedgerAR.WBS2 AND AR.WBS3 = LedgerAR.WBS3 AND
AR.Invoice = LedgerAR.Invoice LEFT JOIN
LD ON PR.WBS1 = LD.WBS1 AND PR.WBS2 = LD.WBS2 AND PR.WBS3 = LD.WBS3 LEFT JOIN
CFGDates ON CFGDates.Period = AR.Period
WHERE (LedgerAR.TransType = 'IN') AND (LedgerAR.SubType <> ' X ' OR
LedgerAR.SubType IS NULL) AND (LedgerAR.AutoEntry <> ' Y ') AND (LedgerAR.Period <= 200408) AND (LedgerAR.Amount <> 0) AND
(AR.PaidPeriod > 200408) AND (PR.WBS1 = '001-298') OR
(LedgerAR.TransType = ' CR ') AND (LedgerAR.SubType IN (' R ', ' T ')) AND (LedgerAR.AutoEntry <> ' Y ') AND (LedgerAR.Period <= 200408) AND
(LedgerAR.Amount <> 0) AND (PR.WBS1 = '001 - 298 ')
GROUP BY PR.WBS1, PR.Name, AR.InvoiceDate, AR.Invoice, Ar.Period, CFGDates.AccountPdEnd
HAVING SUM(CASE WHEN LedgerAR.TransType = 'IN' THEN - 1 * LedgerAR.Amount ELSE LedgerAR.Amount END) <> 0

Within the DateDiff function I need to find the end of the period using a case statment such as

Case When AR.Period='200408' Then Min(CFGDates.AccountPdEnd) Else '0' End As EndPeriod

The problem is that I am having a hard time integrating this into the top query. By using the case statement that I wrote above, I get an error stating that there is a problem near 'As' . I am wondering if there is a way to perform a case statement within a case statement.

Hope that clears things up.

Thanks,
Laura|||that's right, you cannot assign an alias to a value if that value is inside a function

just drop the As EndPeriod

oh, and note that you are looking for the difference in days between AR.InvoiceDate and the value of this case expression, so make sure not to use quotes around the zero if indeed you want december 31, 1899, which seems rather unlikely, but that is, i think, the date that corresponds to zero|||Here is a CASE statement that incorporates your logic:

CASE WHEN (AR.InvoiceDate = '') THEN '0'
WHEN AR.Period='200408' THEN DATEDIFF(day, AR.InvoiceDate, Min(CFGDates.AccountPdEnd))
ELSE DATEDIFF(day, AR.InvoiceDate, 0)
END AS DaysOld

...but whether it will integrate with the rest of your SQL statement, I do not know.|||blindman, that's the same as the nested version (you are allowed to nest CASEs, you know)

that date equal to an empty string gives me the creeps

and the quotes around the zero don't make me feel too hot either

also, i just noticed, CFGDates.AccountPdEnd is in the GROUP BY, so why even bother finding the MIN for it in the DATEDIFF, eh|||Oh, I certainly didn't mean to imply that was ALL that was wrong with her code.

What gives me the heebie-jeebies about it is all the hard-coded values.