How to add Values

Hi

I want to say thank you all for your help. I have one more question. How do I add a field from a form to a field in mysql database. What I want is if the field on the form has 200 and the field in the database has 200 then the field updates to 400 when I hit the submit button. What I am not sure of do I need to query the database first and then add them together?

Here is what I have for now.

$query = "UPDATE Points_Rewards Set Bank = '$bank', Reward_1 = ('$reward1' + Reward_1), Reward_2 = ('$reward2' + Reward_2), Reward_3 = ('$reward3' + Reward_3) WHERE Member_ID = '$memid'";
$result = mysql_query($query) or die(mysql_error());