Notice

• Never believe the user cause there is any input can accepted from user, so verify the input is required which can limit and prevent issue from outside. With client can verify with JS script side, with server can verify the parameters by regular expression.

• With regular is a little bit easy to make mistake, but it can be used.

• To avoid the multiple submit of form, can use flag to distiguish whether the form is submit already. The thought can use in somewhere which need distiguish by flag.