c.php
<?php
$dbc= @mysqli_connect("localhost", "root", "root", "sitename")or die('Error:'.mysqli_connect_error());
index.php
<?php
require("c.php");$sql="select * from user";
$rs=mysqli_query($dbc,$sql);
while($row=mysqli_fetch_array($rs,MYSQLI_ASSOC)){
$c=$row['last_name'];
echo "$c";
}
?>