From: Tom Lane <tgl@sss.pgh.pa.us>
To: Wells Oliver <wells.oliver@gmail.com>
cc: pgsql-admin <pgsql-admin@postgresql.org>
Subject: Re: plpgsql, dynamic variable lengths..
In-reply-to: 
 <CAOC+FBVDAcHKJXfJhYVf4Et5E6ohbE+Sw4s2jG+ioCCLJOjunw@mail.gmail.com>
References: 
 <CAOC+FBVDAcHKJXfJhYVf4Et5E6ohbE+Sw4s2jG+ioCCLJOjunw@mail.gmail.com>
Comments: In-reply-to Wells Oliver <wells.oliver@gmail.com>
	message dated "Fri, 07 Feb 2020 16:38:12 -0800"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <29968.1581127784.1@sss.pgh.pa.us>
Date: Fri, 07 Feb 2020 21:09:44 -0500
Message-ID: <29969.1581127784@sss.pgh.pa.us>
Precedence: bulk

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