RE: Help with a fairly basic SQL (I think)

I have only had that message when the field (LOCN in this case) is NOT
unique Try the following SQL select LOCN, count(*) from tomh/locnmstrpf
group by LOCN having count(*) >
2

and
select LOCN, count(*) from adp/locnmstrpf group by LOCN having count(*)

2

if you get a display in either one then LOCN is NOT unique

Your subquery is this:

select a.printer from tomh/locnmstrpf a, adp/locnmstrpf b where
a.locn=b.locn and a.printer<>' ' and b.printer=' '

If you run that, you will find that it returns all rows except those where
the printer is not blank or there's no match on locn. Your "Where exists"
clause may as well say "WHERE 1 < 2" for all the good it does.

Simplify.

Update mytable a
Set myfield = (select b.myfield
from backuptable b
where a.keydata = b.keydata
)

Dennis Lovelady
http://www.linkedin.com/in/dennislovelady
--
"God bless the Holy Trinity"
-- placard in a Dublin parade