mysql prevent negative numbers

Question

Is their an int field in mysql where negative numbers are not allowed? or more specifically if a negative number is inserted into the field it will insert a zero. I ask this because we have a scoring system and we don't allow people to have negative scores. So if their score does reach bellow zero, it will just insert a zero instead. I'm trying to do this without having to query the user's score to check if it will fall bellow zero.

Answer 1

In addition to the DDL change (INT UNSIGNED) that others have recommended, I'd also change your application logic. You say:

I'm trying to do this without having to query the user's score to check if it will fall bellow zero.

You don't have to explicitly check in a separate query:

UPDATE your_table
   SET score = GREATEST(score + ?, 0) -- This '?' is the adjustment to the score
 WHERE user_id = ?

Now your application cannot UPDATE score to fall below zero, nor will it generate errors or warnings depending on the SQL mode.