What should every PHP programmer know?

First off, there is no must know about learning PHP and MySQL... You go into it not knowing anything, and you'll come out of it knowing a bunch. If there was a must know, then nobody would be able to get into PHP and MySQL development. I personally think you are at a slight advantage going into this without knowing everything about it. It'll give you a fresh perspective and a think outside of the box attitude :)

As far as the object oriented stuff in this thread, it's true. But, as others have said, it's completely up to the programmer (you) to decide how to write your code. You can use object oriented practices, make a spaghetti code junction, or just right a bunch of functions, or whatever. Either way, as everyone else has been saying, it's up to you :)

IRC channel:

Don't really need this, but I find it helpful... See you in here :)


Manual:

The manual is your friend and probably the only thing you should know before diving in.

1. http://www.php.net/manual/en/

2. http://dev.mysql.com/doc/refman/5.0/en/apis-php.html

Frameworks:

Make sure it's an MVC framework :)

1. http://www.cakephp.org/

2. http://www.phpmvc.net/

3. http://www.codeigniter.com/

4. http://www.symfony.com/

IDE:

Whatever suits you best :)

1. http://www.eclipse.org/

2. http://www.vim.org/

3. http://www.zend.com/en/products/studio/

4. http://php.netbeans.org/

Template engines:

PHP is a good template engine

Model view controller frameworks help with this

Ajax:

1. http://jquery.com/

2. http://www.mootools.net/

3. http://developer.yahoo.com/yui/

4. http://www.prototypejs.org/

5. http://www.extjs.com/

6. http://code.google.com/webtoolkit/

CSS:

1. http://www.yaml.de/en/home.html

2. http://code.google.com/p/blueprintcss/

3. http://developer.yahoo.com/yui/reset/

Definitely not an exhaustive list, and things change constantly... But, it's a start :)

Have fun!


Source: stackoverflow.com