Run the following Homebrew commands to install PHP and MySQL:
brew update
brew install php56
brew install mysql
mysql.server start
Then test and configure PHP:
/usr/local/Cellar/php56/5.6.0/bin/php --version (should yield PHP 5.6.0 (cli))
edit ~/.config/fish/fish.config or ~/.bash_profile
add the line alias php='/usr/local/Cellar/php56/5.6.0/bin/php'
php --version (should yield PHP 5.6.0 (cli))