To Connect Mysql Database in PHP :
PHP mysqli_connect() function is used to connect with MySQL database. It returns resource if connection is established or null.
Below code snippet will allow you to connect to MySQL database in PHP.

Example :

   $dbhost = 'localhost';  // database server ip address
   $dbuser = 'username';   // database username
   $dbpass = 'password';   // database password
   // Create connection
   $conn = new mysqli($dbhost, $dbuser, $dbpass);
   if ($conn->connect_error)
     die('Unable to connect to MySQL database: ' . $conn->connect_error);
   echo 'Connected to MySQL database Successfully';
   mysqli_close($conn); // Closing connection

  Output :

  Connected to MySQL database successfully