Inserting symbols into a mysql database from PHP

Hi all, My problem is that that I have a form that takes user data and inserts it into a database. How can I allow quote marks to be inserted into the database? ie if someone puts a " mark in the form field then php/mysql recognises that as the end of the data I'm trying to insert. I tried urlencode-ing the data before inserting it and urldecode-ing it when reading it, but it didn't help. Any suggestions? Surely this must be possible? Thanks in advance Ross