increasing a field by 1

GoGnaget

How is the best way to query mysql to increase a field by one?

This is what want to do:

I have some info about a user in a database, and each time the user logs in I want to increase the field "num_of_logins" (which is a small_int UNSIGNED) by one.
Do I have to do a SELECT-query first to get the value of "num_of_logins" then increase the value by one, and then do a UPDATE-query, or is there a better and faster way to just increase the small_int value directly in the UPDATE-query?

/Josef

bernouli

in mysql there is an option auto increment, to increase the number by 1 automatically

GoGnaget

Originally posted by bernouli
in mysql there is an option auto increment, to increase the number by 1 automatically

But how do I use that then?
I don't think the auto_increment works the way I want it to? auto_increment just adds 1 to a value each time you add a new post...That's not what I wanted...

Correct me if I've missunderstood the auto_increment function.

bernouli

ic, then all you have to do, is get the number from the field, increase it manually by one, and put it again in the field

goa103

hi,

here is the little SQL query I use for my own visitor counter:

mysql_query ("UPDATE my_table SET nb_visitor=nb_visitor+1 WHERE id='" . $id_row . "'");

the AUTO_INCREMENT feature is only useful for primary key. when you create a new entry its id is set to "last_id" + 1. you can get that value with the mysql_insert_id () php function.

Lars_Berg

e.g.

update usertable set num_of_logins = num_of_logins + 1
 where primaryKeyColumn = 4711

GoGnaget

Originally posted by Lars Berg
e.g.
update usertable set num_of_logins = num_of_logins + 1
 where primaryKeyColumn = 4711
[/B]

Perfect! Thanks a lot!

GoGnaget

Originally posted by Lars Berg
e.g.
update usertable set num_of_logins = num_of_logins + 1
 where primaryKeyColumn = 4711
[/B]

Perfect! Thanks a lot!