validate list control value

Since I am new to working with C# asp.net 2010, I am asking the question on how to validate a checkbox list control.

I am adding a new checkboxlist control to a new C# asp.net 2010 web page I am in the process of working on. I am loading the values of the checkbox list controls from values I obtain in a sql server 2008 r2 database.

However, I would like to validate that at least one item in the checkbox list control has actually been selected. I would like to use a validator like the 'required validator' , 'custom validator', or some other validator to make certain the user selected something. I will run the validation when the user clicks the submit button.

Thus how would you accomplish this goal I have for using the validators? If my preferred method does not work, how would you validate that a checkbox list control has been checked? I do not want to update the database until the user has selected something.