Help with a regular expression for 0,1 or 2 decimal places

Hi, I am trying to create a regular expression for a width of a room, the value can be a whole integer (up to 999) with up to 2 decimal places -when it is stored in the database mysql will pad the value accordingly. /^[0-9]{1,3}.?[0-9]{0,2}?$/ The only problem I have found with above is that I can enter 1. Is it possible to modify it so that I can only enter the decimal point if I enter at least digit after it? Also is there any difference between [0-9] and \d Thanks for your help