Question

I need a way to store and manipulate a date range using C# and storing the data in a SQL database. Is storing two DateTimes the best way to go about this?

For example I need to employees to be able to select the duration they spent working on a specific project by selecting the start date and end date using a DatePicker.

I have the following further requirements:

• I need to support half days at start
  and/or end of the duration.
• I need to be able to calculate the number of
  days between the two dates (as a
  double where 0.5 is half a day).
• I need to be able to calculate the
  number of business days between the
  two dates (as a double).
• The time span needs to be displayed on a
  jquery calendar.

• The minimum
  duration is half a day.

  A Date Range of 1/2 Day From 24th May to a full day 27th May:
  2011-05-24 12:00:00.000 => 2011-05-28 00:00:00.000

  A Date Range of Full Day From 24th May to a 1/2 day 27th May:
  2011-05-24 00:00:00.000 => 2011-05-27 12:00:00.000

  A Half Day on 24th May:
  2011-05-24 12:00:00.000 => 2011-05-25 00:00:00.000

  A Full Day on 24th May:
  2011-05-24 00:00:00.000 => 2011-05-25 00:00:00.000

Does this representation make sense? Should I rather look at storing a DateTime for the StartDate and a TimeSpan taking into account my requirements?

Edit: also

Does my representation of end date make sense? So that 2nd of may will be saved as ‘2011-05-03 00:00:00.000’ because that is when the duration ends. Bearing this in mind I’ll need to subtract a day from the end date when displaying this in a calendar..

Answer 1

I suggest to save the start and end date to your database. The difference can always be calculated.

The critical aspect of date ranges is how to handle the boundaries. You can use a mapper for the start/end date to ensure correct time calculations (Inside/Touching):

// ----------------------------------------------------------------------
public void TimePeriodMapperSample()
{
  TimeCalendar timeCalendar = new TimeCalendar();
  CultureInfo ci = CultureInfo.InvariantCulture;

  DateTime start = new DateTime( 2011, 3, 1, 13, 0, 0 );
  DateTime end = new DateTime( 2011, 3, 1, 14, 0, 0 );

  Console.WriteLine( "Original start: {0}",
                     start.ToString( "HH:mm:ss.fffffff", ci ) );
  // > Original start: 13:00:00.0000000
  Console.WriteLine( "Original end: {0}",
                     end.ToString( "HH:mm:ss.fffffff", ci ) );
  // > Original end: 14:00:00.0000000

  Console.WriteLine( "Mapping offset start: {0}", timeCalendar.StartOffset );
  // > Mapping offset start: 00:00:00
  Console.WriteLine( "Mapping offset end: {0}", timeCalendar.EndOffset );
  // > Mapping offset end: -00:00:00.0000001

  Console.WriteLine( "Mapped start: {0}",
    timeCalendar.MapStart( start ).ToString( "HH:mm:ss.fffffff", ci ) );
  // > Mapped start: 13:00:00.0000000
  Console.WriteLine( "Mapped end: {0}",
    timeCalendar.MapEnd( end ).ToString( "HH:mm:ss.fffffff", ci ) );
  // > Mapped end: 13:59:59.9999999
} // TimePeriodMapperSample

Check out the article Time Period Library for .NET (section Calendar Time Periods).