Hi everybody,

I have the following code

 EnumerableRowCollection<DataRow> query;
                  if (checkType && checkCategory)
                     query = from c in dtMax4SaleLimits.AsEnumerable()
                             where ((2 == c.Field<Byte>("type") && lsn_cat == c.Field<String>("lsn_cat"))
                             || (3 == c.Field<Byte>("type") && lessontype == c.Field<Int32>("lessontype")))
                             && (c.Field<DateTime?>("start_time") < ending_time &&
                                 c.Field<DateTime?>("end_time") > begin_time)
                             select c;
                  else
                  {
                     if (checkCategory)
                        query = from c in dtMax4SaleLimits.AsEnumerable()
                                where (2 == c.Field<Byte>("type") && lsn_cat == c.Field<String>("lsn_cat"))
                                && (c.Field<DateTime?>("start_time") < ending_time &&
                                 c.Field<DateTime?>("end_time") > begin_time)
                                select c;
                     else
                        query = from c in dtMax4SaleLimits.AsEnumerable()
                                where (3 == c.Field<Byte>("type") && lessontype == c.Field<Int32>("lessontype"))
                                && (c.Field<DateTime?>("start_time") < ending_time &&
                                 c.Field<DateTime?>("end_time") > begin_time)
                                select c;
                  }

                  Int32 recordsCount = query.Count();
                  if (0 == recordsCount)

This code in executed in the loop for 10 different time values. However, I noticed that the lesson type and lsn_cat is not matching, therefore every time I'll get 0 rows. So, I am thinking I may try to execute my query first for the conditions without time checks and if it returns 0 rows, there is no need for the loop at all.

The question is - how should I proceed - should I use two separate query variables - one for the main query without the extra date condition and another with the condition or there is a way to re-use the same query variable and add extra where condition?

Thanks in advance.