Hello:
I'm playing around with the syntax of the SELECT.
I have a very simple table (this is a silly example):
create table datos (año int, mes text, valor int);
with a couple tuples:
insert into datos (año, mes, valor) values (1999, 'enero', 100);
insert into datos (año, mes, valor) values (2000, 'enero', 200);
insert into datos (año, mes, valor) values (1999, 'febrero', 300);
I'm trying to JOIN two subselects-in-from clauses and can't get it
right:
SELECT foo1.mes, valor1999 AS "1999", valor2000 AS "2000" FROM
(SELECT valor AS valor1999, mes FROM datos WHERE año=1999) AS foo1
OUTER JOIN
(SELECT valor AS valor2000, mes FROM datos WHERE año=2000) AS foo2
ON foo1.mes=foo2.mes;
ERROR: parser: parse error at or near "OUTER"
If I try to do an INNER JOIN, I get instead
SELECT foo1.mes, valor1999 AS "1999", valor2000 AS "2000" FROM
(SELECT valor AS valor1999, mes FROM datos WHERE año=1999) AS foo1
INNER JOIN
(SELECT valor AS valor2000, mes FROM datos WHERE año=2000) AS foo2
ON foo1.mes=foo2.mes;
ERROR: flatten_join_alias_var: unexpected subtree type
But if I do it like
SELECT foo1.mes, valor1999 AS "1999", valor2000 AS "2000" FROM
(SELECT valor AS valor1999, mes FROM datos WHERE año=1999) AS foo1,
(SELECT valor AS valor2000, mes FROM datos WHERE año=2000) AS foo2
WHERE foo1.mes=foo2.mes;
it works (but I lose some tuples -- I expected to get NULL there in the
OUTER JOIN query).
Remember, this is a silly example, I'm not trying to use it for anything
but playing around with the syntax. But I wonder whether this is
supposed to work?
alvherre=> select version();
version
----------------------------------------------------------------
PostgreSQL 7.3devel on i686-pc-linux-gnu, compiled by GCC 2.96
(1 row)
On a related note, psql's "\h select" shows the syntax for select, but
it doesn't specify what are the terminal symbols for the join_type
non-terminal.
(this is a week-old or so CVS)
--
Alvaro Herrera (<alvherre[a]atentus.com>)
"Puedes vivir solo una vez, pero si lo haces bien, una vez es suficiente"
