Re: Error with union in sub-selects

Martin Neimeier wrote:

> Hello,
> some additional informations:
>
> - if i execute the subselect alone, it works fine !.
> - The same select statement works with sybase and oracle, so i think its a legal statement.
> - After reading in the sql2-standard, i have found nothing which restricts unions in sub-selects.
>

Create a temp table (I did it this way):

instead of
select x from table where x in (select A union select B);

create temp table t1 (x type_of_x; );
insert into t1 select A union select B;
select x from table where exists (select t1.x from t1 where t1.x=table.x);

Using exists instead of in circumvents another restriction of PostgreSQL.

Tom Lane said, these bugs would be addressed during the query tree reorganization (7.2, in 2001)

>
> (I don't want to use another rdbms ... i want to use PostgreSQL :-)))))
>
> If somebody has a workaround, then i am the happiest person for the day.

Could be ... if you can live with this ...

Christof

Martin Neimeier (nei(at)ibn(dot)de) reports a bug with a severity of 1
The lower the number the more severe it is.

Short Description
Error with union in sub-selects

Long Description
Version: PostgreSQL 7.0.2 on i686-pc-linux-gnu, compiled by gcc 2.95.2

If i try to use unions in a subselect, postgres reports an parser-error.

ERROR: parser: parse error at or near "union"

see Example. (stipped to essentials)

Sample Code
create table product
(
id int4 not null, -- internal id of product
name TEXT not null, -- name of the product
price numeric not null, -- the price of the product
constraint product_pk
primary key (id)
);

create table product_special
(
id int4 not null, -- internal id of product_special
product_id int4 not null, -- reference to product
start_date date not null, -- when does the special starts
end_date date not null, -- when does the special ends
price numeric not null, -- modified price of product in special-period
constraint product_special_pk -- pk
primary key(id),
constraint product_special_fk1 -- fk to product->id
foreign key (product_id)
references product(id)
match full
on delete cascade
on update cascade
deferrable
);

INSERT INTO product
(id,name,price) VALUES
(1,'Merlot 1996','10.00');
INSERT INTO product
(id,name,price) VALUES
(2,'Gaya & Ray 1994','8.00');

INSERT INTO product_special
(id,product_id,start_date,end_date,price) VALUES (1,1,'2000-09-01','2000-11-30','8.00');

INSERT INTO product_special
(id,product_id,start_date,end_date,price) VALUES (2,2,'2000-01-01','2000-12-02','7.00');

SELECT
p.id as id,
p.name as name
from product p
where
p.id in (select id
from product
where
price >= '9.00' and
price <= '50' and
id not in (select product_id
from product_special
where
start_date <= '2000-9-6' and
end_date >= '2000-9-6')

union

select product_id as id
from product_special
where
price >= '9.00' and
price <= '50' and
start_date <= '2000-9-6' and
end_date >= '2000-9-6');

No file was uploaded with this report

Hello,
some additional informations:

- if i execute the subselect alone, it works fine !.
- The same select statement works with sybase and oracle, so i think its a legal statement.
- After reading in the sql2-standard, i have found nothing which restricts unions in sub-selects.

(I don't want to use another rdbms ... i want to use PostgreSQL :-)))))

If somebody has a workaround, then i am the happiest person for the day.

cu
Martin

--
Martin Neimeier
Ingenieur-Buero Neimeier
Schwarzach / Germany
mailto:nei(at)ibn(dot)de / http://www.ibn.de (under heavy reconstruction)
Tel:+49(6262)912344 / Fax:+49(6262)912347