update query with a sub query

[chainedtodesk]

i have a table that an occasional user will not populate a major field, and i need to catch this before it goes any further. i tried the following code for an update prior to pushing this data out but the query fails. the two tables are large and have multiple records but the main links are distinct and should in theory fix this issue. i am sure its a small code error somewhere but i have rewritten it several times and ways and still it fails. any thoughts?? thanks (error is t1 not defined)

UPDATE RKBOOKTEST t0
SET t0.JQCHNB = t1.JQCHNB
from
(
select distinct JQCVNB,JQCANB,JQC0CD,JQCHNB
from amflib.MTHACTT0 where JQCHNB not in (0,1)
) t1
WHERE
t0.JQCHNB = 0 and
t0.JQCVNB = t1.JQCVNB and
t0.JQCANB = t1.JQCANB and
t0.JQC0CD = t1.JQC0CD

 

[chainedtodesk]

problem solved, thanks for all that helped: here is the working code:

UPDATE RKBOOKTEST SET (JQCHNB) =
(SELECT RKBOOKUPD.JQCHNB
FROM RKBOOKUPD
WHERE RKBOOKTEST.JQCVNB = RKBOOKUPD.JQCVNB
AND RKBOOKTEST.JQCANB = RKBOOKUPD.JQCANB
AND RKBOOKTEST.JQC0CD = RKBOOKUPD.JQC0CD
AND RKBOOKUPD.JQCHNB not in (0,1)
AND RKBOOKTEST.JQCHNB = 0)
WHERE EXISTS
(SELECT RKBOOKUPD.JQCHNB
FROM RKBOOKUPD
WHERE RKBOOKTEST.JQCVNB = RKBOOKUPD.JQCVNB
AND RKBOOKTEST.JQCANB = RKBOOKUPD.JQCANB
AND RKBOOKTEST.JQC0CD = RKBOOKUPD.JQC0CD
AND RKBOOKUPD.JQCHNB not in (0,1)
AND RKBOOKTEST.JQCHNB = 0)