$sql="UPDATE customer SET
name_cus='$name',address_cus='$address',id_national='$id_national',tel_cus='$tel' ,username='$username',password='$password' where username='$username'
";
mysql_query(sql) or die ("SQL ERROR");
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'sql' at line 1
ขึ้นตามนี้เลยครับ
$sql="UPDATE customer SET
name_cus='$name',address_cus='$address',id_national='$id_national',tel_cus='$tel',username='$username',password='$password' where username='$username'
";
mysql_query($sql) or die ("SQL ERROR");