multiple drop downs and a textbox

[Anon]

I'm building a site about dvd's and its backend is able to insert complete reviews in a mysql database. but I seem to have a problem with for example the cast of actors thats playing in the movie. I have a table of persons and a table with personid and reviewid. the admin should be able to pick a actor if he's already in the table and if he isn't his name can be noted in a textbox and he wil be inserted. the exact problem is how to write an easy and short algorithm to put this al in the database.

[Anon]

Just make the non selected value in your actor drop down list to be value=0. Then do a check to see if this value is greater than 0, if so then just insert the id, if not then check to see if the field is filled out and insert that data into your actors table then use that id to fill out the other record.