Compare group of tags to find similarity/score with PHP/MySQL

Question

How can I compare a group of tags to another post\'s tags in my database to get related posts?

What I\'m trying to do is compare a group of tags

Answer 1

Put the tags into an array. Each array being respectively called Post A / Post B etc. Then use array_diff_assoc(), to figure out how different the arrays are.

But really, Ivars solution would work better, this is easier to understand though :)