Re: UPDATE with multiple WHERE conditions

On 6/12/24 15:48, Ron Johnson wrote:
> On Wed, Jun 12, 2024 at 5:28 PM Rich Shepard 
> <rshepard@appl-ecosys.com> wrote:
>
>     I have a table with 3492 rows. I want to update a boolean column from
>     'false' to 'true' for 295 rows based on the value of another column.
>
>     Is there a way to access a file with those condition values? If
>     not, should
>     I create a temporary table with one column containing those
>     values, or do I
>     write a psql script with 295 lines, one for each row to be updated?
>
>
> A plain UPDATE might work.
> UPDATE to_be_updated a
> SET bool_col = true
> FROM other_table b
> WHERE a.pk <http://a.pk> = b.pk <http://b.pk>
>   AND b.field3 = mumble;
>
> (You can join them, right?)
Add "begin;" to that and try it.  If you don't get exactly UPDATE 295 
reported, then "rollback;";