PHP同时操作多个MySQL连接

<?php
$con_1 = mysql_connect('localhost','root','')or die("<font color=red>不能连接数据库！</font>");
mysql_select_db('gameupload',$con_1);
$con_2 = mysql_connect('localhost','root','')or die("<font color=red>不能连接数据库！</font>");
mysql_select_db('blog4',$con_2);
$sql = "select * from user limit 2";
$res = mysql_query($sql,$con_1);
echo mysql_error();
while($row = mysql_fetch_assoc($res)){
print_r($row);
}
?>

<?php
$con_1 = mysql_connect('localhost','root','')or die("<font color=red>不能连接数据库！</font>");
mysql_select_db('gameupload',$con_1);
$con_2 = mysql_connect('127.0.0.1','root','')or die("<font color=red>不能连接数据库！</font>");
mysql_select_db('blog4',$con_2);
$sql = "select * from user limit 2";
$res = mysql_query($sql,$con_1);
echo mysql_error();
while($row = mysql_fetch_assoc($res)){
print_r($row);
}
?>