How to edit value after using query task in arcgis api for silverlight

[Duc_HoaiLuu]

I have a dynamic layer and point feature layer, however I want to query in dynamic layer to get geometry and then select all point with this geometry in feature layer. Then, I will edit those value.  I want to ask how can I select those points with geometry that I have in query task. Please help me, because data is too large so that people cannot click in feature layer. Thank for reading

[DominiqueBroux]

If the amount of data is the problem, I would suggest to use the FeatureLayer OnDemand mode AND to set the feature layer MaximumResolution.

With these settings only the data for the current extent are loaded AND the feature layer is not displayed at large scale where too much data would be loaded.

Additionally you can set an ArcGISDynamiMapServiceLayer visible at large scale that would display the features without allowing edition.

[JenniferNery]

I'm not sure I understood correctly but it sounds like you're doing something similar to this SDK sample ArcGIS API for Silverlight - Interactive Samples | ArcGIS for Developers

You can use ArcGISDynamicMapServiceLayer to render all features (server-side rendering). With FeatureLayer in SelectionOnly mode, you can use Editor to select a region where you see features. These features get added to your FeatureLayer and they become available for editing.

Another way is to use IdentifyTask on ArcGISDynamicMapServiceLayer to get the feature you're interested in editing and then use FeatureLayer.ObjectIDs filter. You might need to call FeatureLayer.Update().