basically, when an user registers the account, you generate a confirmation # (I will use GUID), then send the user an email with the confirmation link. the confirmation link is the url of the confirmation page with the confirmation # as parameter, i.e. www.mysite.com/confirmation.aspx?code={guid} . you save the confirmation code in the database with the user account table (it could be in the same table or a separated table). the user has to click the confirmation url to confirm. when confirm, you just need to check whether the code is the same as the Guid in the database.
Basically, the process is the same and it has no much relation with mySQL or SQL Server.
here is an example, although it is C#, the same process, just a little bit different syntax in code:
http://www.webreference.com/programming/asp_net/registration-confirmation-system/index.html
also
asp.net confirmation mail send link that contains a unique identifier