Storing indefinite arrays in database

Hi, I'am very new to PHP, so please any comment is welcome. I want to write a function in PHP, which takes X arguments and outputs a value. The functioning of this function should be stored in a db (mydb? or better alternatives?) The function would look up the result in the db based on the X arguments. But how can I store X arguments and the corresponding output value? If I limit the X arguments to a specific number like N=10, then I could create N=10 +1 columns in a table. But how should I do it if I don't want to limit myself to a fix number? Thanks for any comment! Ben