Re: [SQL] How to get the max on a char column?

[Rodrigo Carvalhaes]

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 <[EMAIL PROTECTED]> 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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