MySQL Error: Access denied for user 'admin'@'localhost' (using password: NO)

[فال]

define('localhost', 'DATABASEHOST');  // Add the Database Host Server Name. localhost in general cases. 
define('admin_g', 'DATABASENAME'); // Add Name of Database Here
define('admin_gu', 'DATABASEUSER'); // Add Database Username here
define('1234', 'PASSWORD'); //Mysql User Password