how to connect to database

how to connect to database
	above image displays list of servers available in the php my admin
<?php
mysqli_connect('localhost', 'root', '');	to conect to the server using mysqli_connect ,  use arguments ist one is host , and username and password
?>	if it is connceted, nothing it displays, if we write excho, it shows it conncected
store into variables and connect
<?php
$host = 'localhost';	if it is conncected to server , otherewise if it cant connect, it shows , could not open
$user = 'root';
$pass = '';
@mysqli_connect($host, $user, $pass) or die('could not open');
?>
<?php
$host = 'localhost';
$user = 'root';
$pass = '';
@mysqli_connect($host, $user, $pass) or die('could not open');	if it is connected to the server, it will go to next otherewise it wil not eexecute next statements
echo 'connected to the server';	if it is conncected, it displays,, connected to the serverd
	we connected to the server, we have to conncect to the data base
@mysqli_select_db(@mysqli_connect($host, $user, $pass), 'mydatabase') or die('could not connect');	from server, it connects to the data base, if not conccet, it wil die and display could not coonce
echo 'connected to the db';	if it successfully connect to the data base,, it wil  show the connected to database
?>