<?
$cnt=mysql_connect("localhost","admin","somewords");
if($cnt==0)
{
echo "Couldn't connect";
exit;
}
mysql_select_db("mydb");
......
.....
?>

<?
include("myclass.inc");
$param=new veritabani();
$cnt=mysql_connect(trim($param->host),trim($param->user),trim($param->psw));
if($cnt==0)
{
echo "Couldn't connect";
exit;
}
mysql_select_db("db"); /// error from here.
...
.....
.....
?>

<?
class  veritabani{
  var $host;
  var $user;
  var $psw;  
  function varitabani() {
       if(file_exists("config.inc"))
       { $fp=fopen("config.inc","r");
         $this->host=fgets($fp);
         $this->user=fgets($fp);
                  $this->psw=fgets($fp);
                 fclose($fp);
       }
   }  
};
?>

<?php

include("myclass.inc");
$param=new veritabani();
$cnt=mysql_connect(trim($param->host),trim($param->user),trim($param->psw));
if( !is_resource($cnt) )
{
  echo "Couldn't connect";
  exit;
}
mysql_select_db("ericdb", $cnt );


?>

<?
class DB {
   function DB() {
       $this->host = "localhost";
       $this->db = "mydb";
       $this->user = "root";
       $this->pass = "somewords";
       $this->link = mysql_connect($this->host, $this->user, $this->pass);
       mysql_select_db($this->db);
       register_shutdown_function($this->close);
   }
   function close() {
       mysql_close($this->link);
   }
}
?>

if(file_exists("config.inc"))
{include("config.inc");
$DB_admin = new DB();
if($DB_admin==0){
echo 'Couldn\'t connect to MySqle ';
exit;
}
}
else
{echo "<H2>Error!</H2>\n";
 echo "<H2>Couldn't find Config.inc, control it!</H2>\n";
}