Re: How can I use a dynamic column name after NEW. or OLD. in trigger procedure? - Mailing list pgsql-general

On 01/19/2016 11:05 PM, Peter Devoy wrote:
> As part of the extension I am writing I am trying to create a trigger
> procedure in which the value of the primary key of the NEW or OLD row
> is used. The trigger will be fired by arbitrary tables so the column
> name must be dynamic.  Something like:
>
>         pk_column := 'foo_id'; --example assignment only
>
>         EXECUTE 'INSERT INTO  bar (baz) VALUES ($1)'
>         USING NEW.quote_literal(pk_column);
>
> Out of desperation I have pretty much brute forced many weird
> combinations of quote_literal, quote_ident, ::regclass, || and USING.
> Unfortunately, I have not been able to get anything to work so any
> help would be very much appreciated.

Everything gets easier when you use format(). The following should do
what you want:

    EXECUTE format('INSERT INTO bar (baz) VALUES (($1).%L)', pk_column)
        USING NEW;
--
Vik Fearing                                          +33 6 46 75 15 36
http://2ndQuadrant.fr     PostgreSQL : Expertise, Formation et Support