Update Field In Two Tables

This is my curren code for updaing ESN number. But this is incorrect.

<asp:SqlDataSource ID="ESNTrackingDataSource"
UpdateCommand="UPDATE [ESNTracking] SET [EsnNumber] = @EsnNumber WHERE [EsnTrackingId] = @EsnTrackingId"
OnInit="ESNTrackingDataSource_Init"
OnUpdating="ESNTrackingDataSource_Updating"
OnUpdated="ESNTrackingDataSource_Updated"
runat="server">
<UpdateParameters>
<asp:Parameter Type="String" Name="EsnNumber"></asp:Parameter>
</UpdateParameters>
</asp:SqlDataSource>

this is the Select statment I am trying to use so that I can update the Asset in Assets table and the ESN number in the ESN table. But using ESNId and AssetId.

This is my query that returns the ones are not assigned to and
Asset

SELECT DISTINCT EsnId, EsnNumber
FROM dbo.ESNTracking
WHERE (EsnId NOT IN (SELECT EsnId FROM dbo.EsnAsset))