SPDataSource.Selecting event

Occurs immediately before a data retrieval operation.

Namespace:  Microsoft.SharePoint.WebControls
Assembly:  Microsoft.SharePoint (in Microsoft.SharePoint.dll)

public event EventHandler Selecting

The Selecting event is raised immediately before data is retrieved from the underlying data source. To handle the event, register your handler with the Selecting event by using the += event accessors in C# or the AddHandler statement in Visual Basic.

To prevent the event from being raised, subclass the SPDataSource control and then override the OnSelecting(EventArgs) method.