Re: dynamic plpgsql question

Marc Evans wrote:
>>> How can I get the value of NEW.{column_name} (aka NEW.magic in this
>>> specific test case) into the variable data?
>> EXECUTE 'SELECT ' || NEW.column_name ';' INTO data;
>
> Thanks for the suggestion. Unfortunately, it does not work:
>
> CREATE OR REPLACE FUNCTION foo() RETURNS TRIGGER AS $$
>   DECLARE
>     column_name TEXT := TG_ARGV[0];
>     data TEXT;
>   BEGIN
>     EXECUTE 'SELECT ' || NEW.column_name || ';' INTO date;
>     -- ...
>   END;
> $$ LANGUAGE plpgsql;
>
> c3i=> insert into test_table values (1,1);
> ERROR:  record "new" has no field "column_name"

Writing an SP that fetches an array or a text string with column names
given a table name as input is not that hard to write.

Simply fetch "SELECT column_name FROM information_schema.columns WHERE
schema_name = $1 AND table_name = $2" into an array and use
array_to_string() or some such to make it a comma separated string of
columns. You can use that string in your dynamic query.

Cheers.
--
Alban Hertroys
alban@magproductions.nl

magproductions b.v.

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