Re: Can I start Update row in After Insert trigger function?

On 5/23/22 10:35 AM, Durumdara wrote:
> Hello!
>
> I need to log some row changes in a table with JSON format (row_to_json).
>
> In the Before Update I can select the row into a column with JSON format.
> And in After Update I can log this column into an archive table.
> Plus I have the prior data in the JSON_TEXT field.

You need to read:
https://www.postgresql.org/docs/current/plpgsql-trigger.html

>
> But this technique isn't working in insert, because no OLD.id. and OLD row:
>
>     select row_to_json(thistable) into json_text_var
>     from thistable where id = ???.id;
>     No row!!! Only NEW.nn variables.

Yes an INSERT is a new value only there is no old row(value) available.
In the doc link I posted:

"
TG_OP

     Data type text; a string of INSERT, UPDATE, DELETE, or TRUNCATE
telling for which operation the trigger was fired.
"

Use this to modify what value(NEW/OLD) you are working with. Call
trigger with UPDATE and INSERT.

>
> Version: PGSQL 9.6-11
>
> Thank you for your help!
>
> Best regards,
>     dd
>


--
Adrian Klaver
adrian.klaver@aklaver.com