ArcGIS Pro 查询

 var us_states = MapView.Active.Map.GetLayersAsFlattenedList()
                     .OfType<FeatureLayer>().First(lyr => lyr.Name == "US States");

 QueuedTask.Run(() => {
    us_states.SetDefinitionQuery("STATE_NAME = 'Iowa'");
    //equivalent to...
    var def_query = new DefinitionQuery() {
      Name = "A Name that is Unique",
      WhereClause = "STATE_NAME = 'Iowa'"
   };
   us_states.InsertDefinitionQuery(def_query, true);

   var active_def_query = us_states.ActiveDefinitionQuery;
   string where_clause = us_states.DefinitionQuery;//just the where clause string
   
  //remove the active query
  us_states.RemoveActiveDefinitionQuery();

  //remove using name
  us_states.RemoveDefinitionQueries(new List<string> { def_query.Name });

  //use LINQ to get just a specific query
  var def_query = us_states.DefinitionQueries.FirstOrDefault(
                                         dq => dq.Name == "Query def name");