Fwd: SELECT MAX with char => BUG?

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 ??

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)

Rodrigo Carvalhaes 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 ??

Crazy. And posting to the wrong list - try the general/sql lists for
this sort of thing.

> teste=# CREATE TABLE test ( id char(15), name char(80) ); CREATE

You've defined "id" as char - so it's sorting alphabetically, not
numerically, so 1111 < 2

Just defined "id" as a numeric type.

--
Richard Huxton
Archonet Ltd

Rodrigo Carvalhaes <grupos(at)carvalhaes(dot)net> writes:
> 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 ??

You seem to be confused about the difference between numbers and
character strings. max() on a char(n) column returns the
lexicographically largest item.

regards, tom lane