Help updating table

I am making this happen myself but it is complicated and I could use some help. If anyone knows of an example script somewhere or if they can just help me I will kiss their ass. There are more fields than this and other things going on but in a nutshell my problem looks like this: ******************* User submits form with fields Material#, Weight, Date. Weight can only be 1200lbs per day. If user submitted form exceeds calculation for day's weight a new record is created with the same Material#, Difference of Weight and next days Date. There will usually be a few existing records for any given Date that a new record will be inserted into. -- Christopher King chris@create4u.com