$_sql1 = "SELECT * FROM tb_user where userName = {$_clean[‘userName‘]} ";
        $_result1 = _query($_sql1);
        $_rows1 = _fetch_array($_result1);
        if ( $_rows1>0 ){
        echo "<script>alert(‘帐号已经存在,请更换账号‘);location.href=http://www.mamicode.com/‘user.php‘</script>";
        exit();    
        }    
        else{
        $_sqlAdd = "INSERT INTO tb_user (addDates,addIP,userName,userEmail,u

判断是否存在