Re: trigger to access only the last transaction

On Mon, Mar 9, 2015 at 6:01 AM, avpro avpro <avprowebeden(at)gmail(dot)com> wrote:

> hi all,
>
> i have two tables with several columns:
> table1
> idtaskhistory
> performedat
> ...
> idtask
>
> and
>
> table2
> idtask,
> manualdueat
> .....
>
>
> i created a trigger that does the following:
>
> CREATE TRIGGER del1
> AFTER INSERT
> ON table1
> FOR EACH ROW
> EXECUTE PROCEDURE taskdel;
>
> taskdel:
> CREATE OR REPLACE FUNCTION taskdel()
> RETURNS trigger AS
> $BODY$begin
> update table2
> SET
> manualdueat = null,
> FROM table1,
> where table1.idtask = table2.idtask;
> return new;
> END$BODY$
> LANGUAGE plpgsql VOLATILE
> COST 100;
> ALTER FUNCTION taskdel()
> OWNER TO user1;
>
> my idea was to have the info from column "manualdueat" deleted after the
> table1 has been updated. the problem i face is that all columns from table2
> will be deleted, not only my last entry where the insert has been done (I
> was thinking that table1.idtask = table2.idtask will work, but isn't); my
> question to you would be how to access only the last insert id in table1
> and make this trigger working. or do you have another walk arround?
>

How about querying and order by primary key descending and get the first
one?

> I'm using psql 9.4 on a windows system
>
> thank you for your ideas,
> John
>

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