Need to insert line to database via asp:hyperlinkfield control

I currently have the following functional code for a client to add a course to a external shopping cart.
I need to also write to the database table 'registrants' that this logged in client is registering for this course as the cart does not communicate with the database.
I need to write the userid and courseid to this registrants table.
Can this be done at the same time via a onclick or some other method?
<asp:GridView ID="gridview1" DataSourceID="CoursesDataSource" runat="server" AutoGenerateColumns="False" GridLines="None"> <Columns> <asp:HyperLinkField runat="server" Text="<img src='Images/Exp/add_to_cart.png' border='0'>" DataNavigateUrlFields="CourseTitle,CourseDep ...