Simple IP to Country Php MySQL Application or Script

I currently have a digital advertising platform built with PHP MySQL. Our current challenge is our inability to determine the country of an IP which clicked on any of the ads. The application currently records all IPs which clicks on an advert. TASK: We want a simple PHP script or function which can return the country the IP is coming from. For example an IP like [login to view URL] should return the country it is from which is US. (that is the 2 character acronym of the country). The script should use a simply function which we can use on our current program. This is how the call to the function should be: function IPtoCountry($ip_address) This function should simply just return the 2 character acronym for the country the IP belongs to. The programmer is required to upload the current IP database table for us.