Try this within mysql or fire up DBI and do the following:

alter table TABLE_IN_QUESTION modify FIELD_NAME int unsigned not null 
+auto_increment;
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When inserting, just don't list that field. i.e.

# our table
CREATE TABLE example (
id int unsigned not null primary key auto_increment,
num int,
str varchar(50)
);

# our insert statement
insert into example (num,str) values(5,"hello");

# test and see what we get
select * from example;

+----+------+-------+
| id | num  | str   |
+----+------+-------+
|  1 |    5 | hello |
+----+------+-------+
1 row in set (0.00 sec)
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If you need to get the value the primary key field was set to during insertion, you can call select last_insert_id() as a lone statement and it will return the value.

Hope this helps.

antirice    
The first rule of Perl club is - use Perl
The ith rule of Perl club is - follow rule i - 1 for i > 1