SQL UPDATE: Update a field with a field from another file

Hi list!

This is "my complication" on this simple SQL:

=======================================================
FILE:ITEMBL
FIELDS:
ITNBR - ITEM NUMBER (KEY FIELD)
HOUSE - WAREHOUSE (KEY FIELD)
ITCLS - ITEM CLASS

FILE:ITMRVA
FIELDS:
ITNBR - ITEM NUMBER (KEY FIELD)
STID - SITE ID
ITCLS - ITEM CLASS

Goal: Update ITCLS in ITEMBL with ITCLS in ITMRVA only if:
a) STID = 'J2P'
b) HOUSE = 'JTG'
c) ITEMBL.ITCLS <> ITMRVA.ITCLS
=======================================================

This is the SQL I am doing:
UPDATE ITEMBL A SET A.ITCLS =
(SELECT ITCLS FROM ITMRVA B
WHERE A.ITNBR = B.ITNBR AND B.STID = 'J2P' AND A.ITCLS <> B.ITCLS)
WHERE A.ITNBR = B.ITNBR AND A.HOUSE = 'JTG'
?

The error I am having is: COLUMN QUALIFIER OR TABLE B UNDEFINED. If I
remove the "B" qualifier from the last B.ITNBR in the SQL, then I have
this error instead: NULL VALUES NOT ALLOWED IN COLUMN OR VARIABLE ITCLS.

I can't see what I am doing wrong ... HELP! Thanks in advance!


PETER VIDAL
PALL CORPORATION / SR SYSTEM ANALYST @ WH APPLICATION DEVELOPMENT GROUP
10540 RIDGE RD., SUITE 203, NEW PORT RICHEY, FL 34654-5111
' 727-815-3104 Ä 7 727-815-3120 Ä þ WWW.PALL.COM

?Imagination is more important than knowledge...?
Albert Einstein (1879 - 1955)
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