Since Snow Leopard ships with Apache and PHP preinstalled, there is no need to install third party tools like MAMP to run a local development enviroment. All you have to do is enable PHP in the httpd.conf and install MySQL.

To do so open a terminal window and edit the Apache config file located at /etc/apache2/httpd.conf

Uncomment the line

#LoadModule php5_module        libexec/apache2/libphp5.so

(should be on line 116) by removing the leading #

Restart the webserver with “apachectl restart”

Your apache should now run with php enabled. If you want to check if everything works so far, you can place a php file inside your web directory containing

<?php
  phpinfo();

The result should look something like this

Now that you have PHP running, you most likely want MySQL as well. You can download MySQL here http://dev.mysql.com/downloads/mysql/
Simply run the installation package and make sure to install the MySQL.prefPane as well.
Now you can start MySQL in System Preferences > MySQL

By default the MySQL socket is located in /tmp but PHP is looking for it in /var/mysql/

We can change this by editing the php.ini file.

But first we have to copy the default php.ini.

“sudo cp /etc/php.ini.default /etc/php.ini”

Now open /etc/php.ini and edit line 1216.

It should state:

mysql.default_socket = /tmp/mysql.sock

Save the file and restart Apache again

Finaly, test if PHP can connect to your MySQL server by creating a file in your web directory conatining

<?php
$link = mysql_connect('localhost', 'root', '');
if (!$link) {
die('Could not connect: ' . mysql_error());
}
printf("MySQL server version: %s\n", mysql_get_server_info());
<?php$link = mysql_connect('localhost', 'root', '');if (!$link) {    die('Could not connect: ' . mysql_error());}printf("MySQL server version: %s\n", mysql_get_server_info());

If everything went well the result should look like this: