Case in nested select

Question

I'm having trouble getting a CASE statement to work in a nested select. I think I'm close but I can't quite get the syntax right. So far I've tried:

SELECT l.*,
Credit = (
CASE WHEN ISNULL(M.POSTCODE,'') <> '' THEN
  sum(Credit) from Balance cb Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4)
 ELSE
 sum(Credit) from Balance cb Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4) 
 END 
)
FROM live l INNER JOIN master m on m.ClientID = L.ClientID 
WHERE ClientID = 12345

And also:

SELECT l.*,
(SELECT
CASE WHEN ISNULL(M.POSTCODE,'') <> '' THEN
  sum(Credit) from Balance cb Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4)
 ELSE
 sum(Credit) from Balance cb Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4) 
 END 
) AS Credit
FROM live l INNER JOIN master m on m.ClientID = L.ClientID 
WHERE ClientID = 12345

Which seems to match the MSDN examples at http://msdn.microsoft.com/en-us/library/ms181765.aspx . Am I missing something?

Answer 1

I think you need to add some selects before your sum subqueries.

SELECT l.*,
Credit = (
   CASE WHEN ISNULL(M.POSTCODE,'') <> '' THEN
     (SELECT sum(Credit) from Balance cb Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4))
   ELSE
     (SELECT sum(Credit) from Balance cb Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4))
   END 
) 
FROM live l 
    INNER JOIN master m on m.ClientID = L.ClientID 
WHERE ClientID = 12345

Your select's are also exactly the same, so there isn't really a need for a case unless of course you intend for them to be different.

Answer 2

SELECT l.*,
      CASE 
         WHEN ISNULL(M.POSTCODE,'') <> '' THEN
             (SELECT sum(Credit) 
             from Balance cb 
             Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4))
         ELSE
             (SELECT sum(Credit) 
             from Balance cb 
             Where LEFT(LTrim(cb.AccountHolder),4) LIKE LEFT(LTrim(m.Company),4) )
       END as 'Credit'
FROM live l  INNER JOIN master m 
       on m.ClientID = L.ClientID 
WHERE ClientID = 12345