Slick way to update multiple tables.

You can have an updatable view.

On Thu, Apr 1, 2021 at 12:43 PM Michael Lewis <mlewis@entrata.com> wrote:

You can have an updatable view.

*Show-stopper?*
The defining query of the view must have exactly one entry in the FROM clause,
which can be a table or another updatable view.

Or multiple VIEWs? I've never done VIEWs...

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Joins are allowed though.

postgresql.org/docs/current/sql-createview.html

My apologies. It seems INSTEAD OF triggers are required to implement
updates across multiple tables. I thought not if all were simple joins. My
mistake.

On 4/1/21 11:54 AM, Michael Lewis wrote:

postgresql.org/docs/current/sql-createview.html
<http://postgresql.org/docs/current/sql-createview.html&gt;

My apologies. It seems INSTEAD OF triggers are required to implement
updates across multiple tables. I thought not if all were simple joins.
My mistake.

Even with INSTEAD OF triggers, if you use a view then I suppose you
would be forced to update some of the records more often that necessary?
(Unless your tables are 1-to-1-to-1 of course.) Or if there is some
trick to avoid that I'd be curious to know about it.

Here is something I've done in the past:

WITH
update1(ok) AS (
UPDATE foo SET ... WHERE ...
RETURNING 'ok'
),
update2(ok) AS (
UPDATE bar SET ... WHERE ...
RETURNING 'ok'
),
update3(ok) AS (
UPDATE baz SET ... WHERE ...
RETURNING 'ok'
)
SELECT ok FROM update1
UNION ALL
SELECT ok FROM update2
UNION ALL
SELECT ok FROM update3
;

You could even select different messages from each update if you want to
know how many rows you touched in each table.

--
Paul ~{:-)
pj@illuminatedcomputing.com

On 4/1/21 11:16 AM, Theodore M Rolle, Jr. wrote:

I SELECT items from three tables.

It seems that the only way to put updated fields into their proper table
is to query /each/ field, then UPDATE /each/ table.

Am I missing something here?
Is there a way to do this automatically?

Did you join the three tables when querying?

--
Angular momentum makes the world go 'round.