From: Silke Trißl <trissl@informatik.hu-berlin.de>
To: ashok@kalculate.com, SQL PostgreSQL <pgsql-sql@postgresql.org>
Subject: Re: a wierd query
Date: Thu, 13 May 2004 10:41:10 +0200
Message-ID: <40A334A6.5010400@informatik.hu-berlin.de> (raw)
References: <323910-220045413878445@M2W099.mail2web.com>
ashok@kalculate.com schrieb:
>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.
>
Yes, the follwoing
select t1.string_a from main_table t1
union
select t2.string_b from main_table t2;
>
>4) remarks
>
> i can get the solution using a temporary table and with repeated
> "insert into temporary select $column from main_table"
>
>
Why, SQL does the trick!
>
>thanks in advance
>
>ashok
>
>
>
Silke
>
>
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To: pgsql-sql@postgresql.org
Cc: trissl@informatik.hu-berlin.de
Subject: Re: a wierd query
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