Re: performance question

On Tue, 8 Feb 2005 21:02:19 +0100, "Jan van Veldhuizen" <jan_at_van-veldhuizen.nl> wrote:

>What will be better?
>
>UPDATE table1
>SET table1.some_col =
> (SELECT some_col FROM table2
> WHERE table2.col_id = table1.col_id)
>WHERE EXISTS
> (SELECT null FROM table2
> WHERE table2.col_id = table1.col_id)
>
>or:
>
>CREATE VIEW my_view AS SELECT table1.some_col c1, table2.some_col c2
> WHERE table1.col_id = table2.col_id
>
>UPDATE my_view SET c1 = c2
>
>

The view will be not updatable.

IIRC you'll need to
update
(select table1.some_col c1, table2.some_col c2  from table1, table2
where table1.col_id = table2.col_id)
set c1=c2

--
Sybrand Bakker, Senior Oracle DBA