Re: Specifying text to substitute for NULLs in selects

From: Said Ramirez <sramirez(at)vonage(dot)com>
To: Ivan Sergio Borgonovo <mail(at)webthatworks(dot)it>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Specifying text to substitute for NULLs in selects
Date: 2008-11-07 20:20:24
Message-ID: 4914A308.5040908@vonage.com
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I think you are more after something like

SELECT CASE WHEN foo IS NULL THEN 'NA' END FROM bar.
-Said

Ivan Sergio Borgonovo wrote:
> On Thu, 6 Nov 2008 17:44:42 -0800 (PST)
> pcreso(at)pcreso(dot)com wrote:
>
> >
> > Hi,
> >
> > I can specify the text used to represent a null value in output
> > from copy, but I'd like to do something similar is select output,
> > eg: all NULL values are represented by NA or NaN.
> >
> > I can't find anything in the docs about this.
> >
> > This could be managed using case statements around all the columns
> > in the query, but is there a simpler way, like setting a system
> > variable to specify this?
>
> wtw_drupal=# create schema test;
> CREATE SCHEMA
> wtw_drupal=# create table test.test(c1 text);
> CREATE TABLE
> wtw_drupal=# insert into test.test values(null);
> INSERT 0 1
> wtw_drupal=# insert into test.test values('test');
> INSERT 0 1
> wtw_drupal=# \copy test.test to stdout null as 'BANANA'
> BANANA
> test
> wtw_drupal=# drop schema test cascade;
> NOTICE: drop cascades to table test.test
> DROP SCHEMA
>
> everything clearly explained in the COPY manual:
> http://www.postgresql.org/docs/8.1/static/sql-copy.html
>
> --
> Ivan Sergio Borgonovo
> http://www.webthatworks.it
>
>
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