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;
It looks odd - It is not intuitive, it introduces new inconsistency inside Postgres, or with solutions in other databases. No other database has a similar rule, so users coming from Oracle, Db2, or MSSQL, Firebird will be confused. Users that use PL/pgSQL will be confused.
