Validating dropdownlist asp net
When you used server-side validation with ASP 3.0, if something the user entered was wrong, you could repost the form and ask the user to correct the information in that particular field of the form.
Sometimes, you carried the correct input from the other fields back to the form page, and populated the fields for the users so they didn't have to re-enter the same information again.
Validation server controls are a series of controls that help you validate the data that the user enters into the other controls that are provided with ASP. They determine whether the form can be processed based upon the rules that you define in the validation server controls.
You yourself either programmed it to be client-side or server-side.
Some sites on the Internet don't carry this inputted information back to the form page, and the user is then required to enter all the information into the form a second time.
Obviously, this may cause people to leave your site for another.
You must understand these two different ways of validating the data users input into a Web form.
After the user enters data into a Web form, clicks the Submit button, and sends the form data to the server as a request, you can perform server-side validation on the data.
This paper introduces these new controls and discusses tips and tricks on working with them in practical scenarios.