Query Problem

Folks:

Here's the problem, in abstract:  I need to select every record in table
A that does not have a link in table B Join Table C where Table
C.account = 11

The relevant fields:

Table_A
CaseID
Data

Table_B
GroupID
CaseID
Amount

Table_C
GroupID
AccountID

Thus, I need to select:

SELECT Data FROM Table A 
WHERE CaseID NOT IN (SELECT CaseID FROM Table_B, Table_CWHERE Table_B.GroupID = TableC.GroupID	AND TableC.AccountID = 11)

The problem is, since Table_B and Table_C are large (10,000 records +)
this exclusion query takes several *minutes* to run.

I've fooled around with drectional joins, views, and temporary tables,
but I can seem to find anything that works faster.  Suggestions?

-Josh Berkus

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