I am trying to implement an update statement using a prepared statement in a PHP script, but it appears that it is not updating the record in the database and I am not sure why
Might not help, but why are you only binding 3 variables, when there are 4? I can't say that I have experience doing this in PHP, but in Perl and Oracle it would throw an error. I'd try binding the 2 SETs and the 1 WHERE, and removing the first assignment, and see if that works.