关于php中利用sql语句创建表的有关问题

";
if($_POST)
{
    $user=$_POST["user"];
    $pass=$_POST["pass"];
    $age=$_POST["age"];
    $sex=$_POST["sex"];
    $mail=$_POST["mail"];
    $qq=$_POST["qq"];
    $degree=$_POST["degree"];
    $fav=$_POST["fav"];
    $len=count($fav);
    $fav_z="";
    for($i=0;$i<$len;$i++)
    {
        $fav_z=$fav_z.$fav[$i];
        if($i<$len-1)
            $fav_z=$fav_z.",";
    }
    $con=mysql_connect("localhost","root","");
    mysql_select_db("ceshi");
    mysql_query("set names GB2312");
    $sql="select count(*) from user2 where name='$user'";
    $result=mysql_query($sql);
    $num=mysql_fetch_row($result);
    if($num[0]>0)
    {
        echo "have the same name!try another one.";
    }
    else 
    {
        $sql="insert into user2(name,password,age,sex,mail,qq,degree,fav)value('$user','$pass','$age','$sex','$mail',$qq','$degree','$fav_z')";
        $re=mysql_query($sql);
        if($re)
            echo "insert successful!";
        else echo "insert error~!";
        echo "
";
    }
}
else 
{
    echo "nothing upload!
";
}
echo "
clickthere return";
?>