php中修改信息出现异常，信息修改不了

php中修改信息出现错误，信息修改不了
页面：







error_reporting(E_ALL & ~E_NOTICE);
include_once("../include/conn.php") ;
$com_id=$_GET["com_id"] ;
$mysql="select * from com_table where com_id='$com_id'" ;
$str=mysql_fetch_object(mysql_query($mysql)) ;
$show_number=iconv("gb2312" , "utf-8//IGNORE" , $str->com_number) ;
$show_name=iconv("gb2312" , "utf-8//IGNORE" , $str->com_name) ;
$show_telephone=iconv("gb2312" , "utf-8//IGNORE" , $str->com_telephone) ;
$show_mobile=iconv("gb2312" , "utf-8//IGNORE" , $str->com_mobile) ;
$show_qq=iconv("gb2312" , "utf-8//IGNORE" , $str->com_qq) ;
?>

账号:
姓名:
固定电话:
移动电话:
QQ:

if(isset($_POST["submit"])){
/*
$com_number=trim($_POST["com_number"]) ;
//$com_pwd=trim($_POST["password"]) ;
$com_name=trim($_POST["com_name"]) ;
$com_telephone=trim($_POST["com_telephone"]) ;
$com_mobile=trim($_POST["com_mobile"]) ;
$com_qq=trim($_POST["com_qq"]) ;
*/
$com_number=iconv("utf-8" , "gb2312//IGNORE" , $_POST["com_number"]) ;
//$com_pwd=iconv("utf-8" , "gb2312//IGNORE" , $com_pwd) ;
$com_name=iconv("utf-8" , "gb2312//IGNORE" , $_POST["com_name"]) ;
$com_telephone=iconv("utf-8" , "gb2312//IGNORE" , $_POST["com_telephone"]) ;
$com_mobile=iconv("utf-8" , "gb2312//IGNORE" , $_POST["com_mobile"]) ;