Re: Schema variables - new implementation for Postgres 15

Pavel Stehule:
> Sure there is more possibilities, but I don't want to lost the
> possibility to write code like
>
> CREATE TEMP VARIABLE _x;
>
> LET _x = 'hello';
>
> DO $$
> BEGIN
>   RAISE NOTICE '%', _x;
> END;
> $$;
>
> So I am searching for a way to do it safely, but still intuitive and
> user friendly.

Maybe a middle-way between this and Alvaro's proposal could be:

Whenever you have a FROM clause, a variable must be added to it to be
accessible. When you don't have a FROM clause, you can access it directly.

This would make the following work:

RAISE NOTICE '%', _x;

SELECT _x;

SELECT tbl.*, _x FROM tbl, _x;

SELECT tbl.*, (SELECT _x) FROM tbl, _x;

SELECT tbl.*, (SELECT _x FROM _x) FROM tbl;

But the following would be an error:

SELECT tbl.*, _x FROM tbl;

SELECT tbl.*, (SELECT _x) FROM tbl;

Best,

Wolfgang