update textfield based on dropdown selected

hi!! m a newbie too… and i have a similar prob. i want to create a unique job card id. the value of job card id is based on first two drop downs selected and an incremental number.

eg.first dropdown->computer is chosen,

second dropdown->software is chosen,

then the job card id should be:comp/sw/12

here,"comp" indicates that computer is chosen,

"sw" indicates software is chosen and

12 indicates that this is a 12th entry in the database for computer and software together.

job card id is a textfield which should be automatically field once both the dropdowns are selected.

please share a bit of your knowledge…:)


You can start here.