From: Rodrigo Carvalhaes <grupos@carvalhaes.net>
To: Jeff Eckermann <jeff_eckermann@yahoo.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: How to get the max on a char column?
Date: Sat, 20 Nov 2004 15:54:15 +0000
Message-ID: <419F68A7.70402@carvalhaes.net> (raw)
In-Reply-To: <20041120171339.11400.qmail@web20824.mail.yahoo.com>
References: <20041120171339.11400.qmail@web20824.mail.yahoo.com>
Dear Jeff,
Thank you for your help.
I tried : select max((id::text)::integer) from test;
and works perfectly!
Greetings from Brazil!
Rodrigo Carvalhaes
Jeff Eckermann wrote:
>--- Rodrigo Carvalhaes <grupos@carvalhaes.net> wrote:
>
>
>
>>Hi !
>>
>>I am quite confused of the results on a SELECT
>>max...
>>
>>My environment:
>>Conectiva Linux 10, PostgreSQL 7.4.6 (compiled from
>>the sources)
>>
>>My problem is the "select max(id) FROM test" the
>>result is 20 but the
>>right is 1020. Is this a BUG or I am crazy ??
>>
>>
>
>For a char() column, '20' is the maximum of the values
>that you have inserted, because the comparison is
>text-based, not numeric. If you want numeric sorting,
>you will need to cast the value, like:
>
>select max(cast(id as integer)) from test;
>
>I'm not sure offhand whether in fact a direct cast
>from char() to integer is available; you may need to
>cast to "text" first.
>
>But if you expect to be able to sort numerically, why
>are you not using a numeric datatype?
>
>
>
>>Cheers,
>>
>>Rodrigo Carvalhaes
>>
>>The SQL...
>>
>>teste=# CREATE TABLE test ( id char(15), name
>>char(80) );
>>CREATE TABLE
>>teste=# \d test
>> Table "public.test"
>>Column | Type | Modifiers
>>--------+---------------+-----------
>>id | character(15) |
>>name | character(80) |
>>
>>teste=# INSERT INTO test VALUES ( '10', 'luidgi');
>>INSERT 15303727 1
>>teste=# INSERT INTO test VALUES ( '20', 'luis');
>>INSERT 15303728 1
>>teste=# INSERT INTO test VALUES ( '1010', 'ruan');
>>INSERT 15303729 1
>>teste=# INSERT INTO test VALUES ( '1020', 'lion');
>>INSERT 15303730 1
>>teste=# SELECT * FROM test;
>> id |
>> name
>>
>>
>>
>-----------------+----------------------------------------------------------------------------------
>
>
>>10 | luidgi
>>20 | luis
>>1010 | ruan
>>1020 | lion
>>(4 rows)
>>
>>teste=# SELECT max(id) FROM test;
>>max
>>-----
>>20
>>(1 row)
>>
>>teste=# select max(id) FROM test;
>>max
>>-----
>>20
>>(1 row)
>>
>>
>>
>>
>>
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>
>
>
>
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To: pgsql-sql@postgresql.org
Cc: grupos@carvalhaes.net, jeff_eckermann@yahoo.com
Subject: Re: How to get the max on a char column?
In-Reply-To: <419F68A7.70402@carvalhaes.net>
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