Sometimes, installing connecting to MySQL from PHP, you will see this error:

#1251 - Client does not support authentication protocol requested by server; consider upgrading MySQL client

This error occurs when you are using are using MySQL 4.1+ with an older version of PHP. Thankfully, you don't have to upgrade anything :). Here's how to fix the problem:

1. Open the command line, and run mysql, like this:
   
   mysql -u root -p
   
   
2. Hit enter, type your password, hit enter again
   
   
3. Run the following command (replace mypassword with your root password):
   
   SET PASSWORD FOR root@localhost = OLD_PASSWORD('mypassword');
   
   
4. Hit enter. Try again,