preg_replce ' for use with mysql

How do I replace all ' with \' in php so that I'm able to use the mysql queries. Note that simply using: preg_replace("/'/", "\'", -1) is not what I'm looking for, for this does not help me. Let's say I take the address from a form and want to enter it into the database as it is. Now, if the user enters "'" the above preg_replace will work but if the user himself enters "\'" , during replacing, the '\' introduced is nulled by the effect of the preceeding back-slash, and the mysql query becomes somthing like: mysq_insert ("insert into students (id, address) values (3, '\\'')"); How do I get around this problem? Is there any function which helps to insert everything into the mysql database as it is (does auto-escaping). Nirnimesh. IIIT-Hyd. India.