Can someone explain the difference in PHP and MySQL?

[Hi there]

I want to start learning how to build and maintain databases... The type of information I want to capture is hospital information on patients since i work in a hospital this will be very beneficial... But ive looked everywhere and i was told to start learning mysql for this but everywhere i look i see php with msql... Is there a difference between the two? Should i learn both together or how do i start... Also if u have any books or websites that might be helpful to learn how to maintain and create databases will be very helpful... thx