PHP Solution Importing CSV File into Database

I am needing a php system in place which I can import a csv file into my database. I am looking for the script to update existing db entries on import but also if the Product SKU is not located in DB then add as a new product. This will be an easy job for someone with experience.

I currently have a index.php file which shows all db entries, I also have a addproduct page for manual entry and then an upload page for csv import