public StudyHistoryCollection FetchAll()
 {
     var coll = new StudyHistoryCollection();
     var qry = new Query(StudyHistory.Schema);
     coll.LoadAndCloseReader(qry.ExecuteReader());
     return coll;
 }
 public StudyHistoryCollection FetchByQuery(Query qry)
 {
     var coll = new StudyHistoryCollection();
     coll.LoadAndCloseReader(qry.ExecuteReader());
     return coll;
 }