Re: a wierd query - Mailing list pgsql-sql

From Peter Childs
Subject Re: a wierd query
Date
Msg-id Pine.LNX.4.58.0405131014500.15412@bluedragon.homelinux.net
Whole thread Raw
In response to a wierd query  ("ashok@kalculate.com" <ashok@kalculate.com>)
List pgsql-sql

On Thu, 13 May 2004, ashok@kalculate.com wrote:

> hi
>
> i have a wierd problem and i require an equally weird query.
> 1) backgound
>   Table test:
>     CREATE TABLE main_table (
>                string_A varchar( 20),
>                string_B varchar( 20),
>                );
>      -- both columns are identical in nature and usage
>      INSERT INTO main_table VALUES('abcd','qrst');
>      INSERT INTO main_table VALUES('efgh','efgh');
>      INSERT INTO main_table VALUES('ijkl','abcd');
>      INSERT INTO main_table VALUES('abcd','ijkl');
>      INSERT INTO main_table VALUES('qrst','uvwx');
>
> 2) problem:
>
>      i require a query that gives me a result set of the form
>
>    'abcd'
>    'efgh'
>    'ijkl'
>    'qrst'
>    'uvwx'
>
>    that is i require the dictinct values from (visualizing each column
> result as a set) the union of the two columns
>
> 3) questions
>
>    a) is a query like this possible that can give me the desired result
>    b) if so what would it be.
>
> 4) remarks
>
>     i can get the solution using a temporary table and with repeated
>       "insert into temporary select $column from main_table"
>
>

select distinct t from (select string_A as t from main_table union
select string_B as t from main_table);

or

select f from (select A as t from main_table union select B as t from
main_table) group by t order by t;

hope that helps

Peter Childs


pgsql-sql by date:

Previous
From: Achilleus Mantzios
Date:
Subject: Re: a wierd query
Next
From: Yasir Malik
Date:
Subject: Re: a wierd query