Securing your MySQL Database is two-fold. Your MySQL Database can be accessed through your PHP Programs as well as through a direct Internet connection. They must both be secured to prevent database hacker attacks.
Most ISPs provide a secure network connection to your MySQL Database by filtering the IPs and servers that may connect to it. They additionally restrict database permissions to specific users on specific IP Addresses and ranges, which can be very effective.
Securing your PHP Programming remains the most critical point in securing your MySQL Database! Bad PHP programmers can devastate your whole Online Business if they include PHP Programming Vulnerabilities and ignore Secure PHP Programming. PHP Programs can be extremely secure, if they are programmed well by qualified and experienced PHP Programmers.