Trigger with dynamic field name

Question

I have a problem on creating PostgreSQL (9.3) trigger on update table. I want set new values in the loop as

EXECUTE \'NEW.\'|| fieldName || \':=\'\'some prep         


        

Answer 1

Your problem is that EXECUTE can only be used to execute SQL statements and not PL/pgSQL statements like the assignment in your question.

You can maybe work around that like this:

Let's assume that table testtab is defined like this:

CREATE TABLE testtab (
   id integer primary key,
   val text
);

Then a trigger function like the following will work:

BEGIN
   EXECUTE 'SELECT $1.id, ''prefix '' || $1.val' INTO NEW USING NEW;
   RETURN NEW;
END;

I used hard-coded idand val in my example, but that is not necessary.