for dev and debug I can recommend PDT:

http://zend.com/pdt

Although sometimes for me when i used to use it, it bugged and the auto-complete died more often than not and it dies when you throw a large project at it.
However the step through debugger can be useful to a beginner so that you can see whats happening.

I personally use vim http://www.vim.org/

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mysql> SELECT * FROM `users` WHERE `users`.`clue` > 0;
Empty set (0.00 sec)