Why isn't my SqlDataSource's UpdateCommand working? - asp.net

Question

<asp:SqlDataSource ID="HopefulDataSource" runat="server"
ConnectionString="<%$ ConnectionStrings:MyConnectionString %>"
SelectCommand= "SELECT id, regGroupID, amountReceived, other FROM table"
UpdateCommand="UPDATE table
SET [amountReceived] = #amountReceived
WHERE [regGroupID] = #regGroupID">
<SelectParameters>
<asp:ControlParameter ControlID="ddlCourses" Name="ddlSelectedCourse" PropertyName="SelectedValue" Type="String" />
</SelectParameters>
<UpdateParameters>
<asp:Parameter Name="regGroupID" Type="Int32" />
<asp:Parameter Name="amountReceived" Type="Decimal" />
other parameters
<asp:Parameter Name="id" Type="Int32" />
</UpdateParameters>
</asp:SqlDataSource>
The above works when I change "WHERE [regGroupID] = #regGroupID" to either
WHERE [id] = #id
or
WHERE [regGroupID] = 2

Answer 1

You need to add "regGroupID" to the DataKeyNames collection in your GridView declaration. Something like this:
<asp:GridView ID="yourGridViewId" DataKeyNames="regGroupID" ... >
...
</asp:GridView>
See the DataKeyNames documentation:
You must set the DataKeyNames property in order for the automatic
update and delete features of the GridView control to work. The values
of these key fields are passed to the data source control in order to
specify the row to update or delete.
Note: it's been a while since I used this, so you might need to include both the primary key, and your other key field. Like this:
DataKeyNames="id,regGroupID"