Chapter 6. Validation
In addition to visual controls, discussed in Chapter 2, which render HTML based on their current state, ASP.NET provides a set of validation controls, which make it simple to add even sophisticated validation to any page. These controls enforce validation constraints on user-populated form data through both client-side and server-side techniques, and are easy to customize in their appearance and their behavior.
It is common and often critical for Web forms to validate user data entry. Forms are used to collect data from users to be stored in databases, and the types of information stored must match the types of the fields in the database used to store them. Furthermore, there are often dependencies on data entered ...