Svein Erling Tysvaerwrote:

> update TableA a
> set a.p=(select b.q from TableB b where b.y=a.x)
> where exists(select * from TableB c where c.y=a.x)

Thank you all! I test it works although I still do not understand why
it work, because I'm not good in working with subquery.

Will it fail if 2 different alias not set for tableB?
eg.
update a
set a.p=(select b.q from b where b.y=a.x)
where exists(select 1 from b where b.y=a.x)

Which method, this and the SP suggested by Adam, is faster? I meant
execution speed for larger table.

regards,
bill