>>>>Hi Rob,
>>>>
>>>>This doesn't seem to work as is
>>>>
>>>>

>>>>  if (resourceEvent)                              
>>>>                  {
>>>>                      // Remove instructors who don't have anything planned
>>>>                      var query = dtInstructors.AsEnumerable().Where(c => dtAllScheduled.AsEnumerable().Any(b =>  1 == b.Field<Byte>("layer") 
>>>>                                          && true==b.Field<Boolean>("schdassign") && c.Field<String>("instr_id")== b.Field<String>("resource_id")
>>>>                                          ));
>>>>                      query.CopyToDataTable(dtInstructors, LoadOption.OverwriteChanges);
>>>>                  }

>>>>
>>>>My dtInstructors has rows but dtAllScheduled does not.
>>>>
>>>>After the query I am supposed to get 0 rows in the dtInstructors but it seems to be the same table as it was before the query. Do you see how can I adjust the code to get the query "overwrite" my original table?
>>>>
>>>>Thanks.
>>>
>>>Is it throwing an InvalidOperationException that is being caught elsewhere? See the conditions for that exception at http://msdn.microsoft.com/en-us/library/bb359707(v=vs.110).aspx
>>
>>Update.
>>
>>I figured this out with the following code:
>>
>>

>>               DataTable dtInstructorsAll = this.GetDataSet().Tables[0];
>>               DataTable dtInstructors;
>>
>>               if (dtInstructorsAll.Rows.Count > 0)
>>               {
>>                  DateTime minDate = Functions.Smallest<DateTime>((DateTime)bRow.StartTime, preferenceStartTime);
>>                  DateTime maxDate = Functions.Largest<DateTime>((DateTime)bRow.EndTime, preferenceEndTime);
>>
>>                  DateRange range = new DateRange(minDate, maxDate);
>>
>>                  // GetPvtSortedResources doesn't not use instructor type where condition while GetPvtSortedSchedule does use it
>>                  DataTable dtAllScheduled = this.GetAllScheduled(sqlCommand, range, (resourceOnly) ? "" : instructorTypeWhere, resourceEvent);
>>                  Logging.LogFormat(4, "Number of eligible bookings returned in csrAllSched: {0}", dtAllScheduled.Rows.Count);
>>
>>                  if (resourceEvent)                              
>>                  {
>>                      // Remove instructors who don't have anything planned
>>                      dtInstructors = dtInstructorsAll.Clone();
>>                      var query = dtInstructorsAll.AsEnumerable().Where(c => dtAllScheduled.AsEnumerable().Any(b =>  1 == b.Field<Byte>("layer") 
>>                                          && true==b.Field<Boolean>("schdassign") && c.Field<String>("instr_id")== b.Field<String>("resource_id")
>>                                          ));
>>                      query.CopyToDataTable(dtInstructors, LoadOption.OverwriteChanges);
>>                  }
>>                      else
>>                  {
>>                      dtInstructors = dtInstructorsAll.Copy();
>>                  }
>>
>>

>>
>>So, I originally create a different table and then either copy or clone and CopyToDataTable depending on my condition.
>>
>>Does it sound like an OK solution?
>
>You should be checking query.Any() prior to doing the CopyToDataTable. CopyToDataTable is supposed to be throwing an InvalidOperationException if the query is empty.

So, do you suggest to add a check for query.Count == 0 prior to CopyToDataTable and in the case of 0 just bail out? May be I would not need the clone and copy at all, e.g. it would work as is in case my query returns rows?