Entity Framework and Linq - Comparing DateTime - asp.net

Question

I have this code
public List<CalendarData> GetCalendarData(DateTime day)
{
List<CalendarData> list = new List<CalendarData>();
using (dataContext = new VTCEntities())
{
DateTime test = new DateTime(2010, 10, 20, 17, 45, 0);
var data = from z in dataContext.ReservationsSet
where z.start_time.Value == test
select z;
foreach (var r in data)
What I'd like to do is have this
var data = from z in dataContext.ReservationsSet
where z.start_time.Value == day
select z;
the problem I have is that z.start_time has the time part also. The DateTime day doesn't have the time part recorded. Is there a way to compare the the date part of without getting this error
The specified type member 'Date' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.
when I do this
var data = from z in dataContext.ReservationsSet
where z.start_time.Value.Date == test
select z;

Answer 1

One option is to compute two values, like this:
DateTime day = ...;
DateTime nextDay = day.AddDays(1);
var data = from z in dataContext.ReservationsSet
where z.start_time.Value >= day &&
z.start_time.Value < nextDay
select z;

Answer 2

You can't use .Date in Entity Framework. The easiest way I know to handle this is to make a minimum + maximum day:
DateTime test = new DateTime(2010, 10, 20, 17, 45, 0);
DateTime startDay = test.Date;
DateTime endDay = startDay.AddDays(1);
var data = from z in dataContext.ReservationsSet
where z.start_time.Value >= startDay && z.start_time.Value < endDay
select z;