What you've described is mainly what PHP is used for. In addition, and depending on what a prospective employer might require, you might also need to know how to use object oriented PHP so that you could utilize code libraries such as
PEAR.
If you'd like to know more about object oriented PHP, I would highly recommend the
PHP Anthology, which is a two-volume set. Sample chapters can be downloaded from both books, one of which is an overview of object oriented PHP. Both books are excellent resources for solutions to common problems encountered by PHP programmers.
Hope this helps.