Hello and thanks for taking the time to help out. I've been tasked
with finding records from one table that are not in another table, but
do exist in a third. I've written a query that identifies the records,
but when I try to add the meaningful data to the select statement, I
find that because I am using "EXCEPT" I needed to add another join (my
selection column list did not match the column list in the EXPCEPT
selection column list) and that's where my problems start! Below find
a simplified version of the SQL I am trying to execute:

SELECT DISTINCT A.XYZ, B.WUV
FROM SCHEMA1.TABLE1 A
INNER JOIN (
SELECT WUV
FROM SCHEMA2.TABLE1) B
ON A.XYZ = B.WUV
INNER JOIN (
SELECT DISTINCT C.WUV
FROM SCHEMA2.TABLE1 C
INNER JOIN SCHEMA1.TABLE1 D
ON C.WUV = D.XYZ
EXCEPT
SELECT DISTINCT E.XYZ
FROM SCHEMA2.TABLE3 E
WHERE E.DATE = (
SELECT F.DATE
FROM SCHEMA2.TABLE1 F
)
AND E.ID = 654321
) XX
ON A.WUV = XX.WUV
WHERE A.ID = 123456
AND A.FLAG = 'Y'
AND A.CODE = 'LMNOP'


When executing this statement the following error is returned:

[[DB2/AIX] SQL0206N "XX.WUV" is not valid in the context where it is
used. SQLSTATE=42703

The problem seems to be with the second INNER JOIN:

....
INNER JOIN (
SELECT DISTINCT C.WUV
FROM SCHEMA2.TABLE1 C
INNER JOIN SCHEMA1.TABLE1 D
ON C.WUV = D.XYZ
EXCEPT
SELECT DISTINCT E.XYZ
FROM SCHEMA2.TABLE3 E
WHERE E.DATE = (
SELECT F.DATE
FROM SCHEMA2.TABLE1 F
)
AND E.ID = 654321
) XX
ON A.WUV = XX.WUV
....

So I ran the sub query within the INNER JOIN:

SELECT DISTINCT C.WUV
FROM SCHEMA2.TABLE1 C
INNER JOIN SCHEMA1.TABLE1 D
ON C.WUV = D.XYZ
EXCEPT
SELECT DISTINCT E.XYZ
FROM SCHEMA2.TABLE3 E
WHERE E.DATE = (
SELECT F.DATE
FROM SCHEMA2.TABLE1 F
)
AND E.ID = 654321

This returned the records I was looking for. The interesting thing is
that the column name was "1". I tried the same sub query and changed
the first line to:

SELECT DISTINCT C.WUV AS WUV_DUM

The column name was still "1".
I believe that this is what is at the heart of my problem. In the ON
part of the JOIN, XX.WUV is not recognized because there appears to be
no XX.WUV.

I'm stumped and could use any and all help to write this correctly!

Thanks!