Re: plpgsql, dynamic variable lengths.. - Mailing list pgsql-admin

From Wells Oliver
Subject Re: plpgsql, dynamic variable lengths..
Date
Msg-id CAOC+FBVj-CuZriMmLa0oEWONuQQmzzLN9Bzu8cF6AGykh+OUmA@mail.gmail.com
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In response to Re: plpgsql, dynamic variable lengths..  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: plpgsql, dynamic variable lengths..  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-admin
Yes, but the issue is it won't always be three params, and not always the same variable in $1, $2, etc. It depends on which keys are present in the passed JSON object. Which I why I think I need to do something else like create a recordset and pass that in USING, or something. Just can't quite figure it out...

On Fri, Feb 7, 2020 at 6:09 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
Wells Oliver <wells.oliver@gmail.com> writes:
> I am trying to create a plpgsql function which accepts a jsonb object as
> its parameter.

> This jsonb can have up to three keys, and I am trying to build out the
> dynamic SQL like this. I want to be able to pass a variable number of
> params to the RETURN QUERY EXECUTE ... USING ... because it can be 0 params
> in the JSONB object, or one, or two.

> What's the missing piece here? How can I adjust my USING to accomplish this?

I think your USING is probably fine.  But you made all the SQL fragments
refer to $1:

> begin
> SQLSTRING := 'SELECT * FROM mytable WHERE true';
> if args->>'col1' is not null then
> SQLSTRING := SQLSTRING || ' AND col1 = $1';
> end if;

> if args->>'col2' is not null then
> SQLSTRING := SQLSTRING || ' AND col2 = $1';
> end if;

> if args->>'col3' is not null then
> SQLSTRING := SQLSTRING || ' AND col3 = $1';
> end if;

Of course those need to be $1, $2, $3.

                        regards, tom lane


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