How to compare only date components from DateTime in EF?

I am having two date values, one already stored in the database and the other selected by the user using DatePicker. The use case is to search for a particular date from the database.

The value previously entered in the database always has time component of 12:00:00, where as the date entered from picker has different time component.

I am interested in only the date components and would like to ignore the time component.

What are the ways to do this comparison in C#?

Also, how to do this in LINQ?

UPDATE: On LINQ to Entities, the following works fine.

e => DateTime.Compare(e.FirstDate.Value, SecondDate) >= 0

Solution 1:

Use the class EntityFunctions for trimming the time portion.

using System.Data.Objects;    

var bla = (from log in context.Contacts
           where EntityFunctions.TruncateTime(log.ModifiedDate) ==  EntityFunctions.TruncateTime(today.Date)
           select log).FirstOrDefault();

Source: http://social.msdn.microsoft.com/Forums/en-US/csharpgeneral/thread/84d4e18b-7545-419b-9826-53ff1a0e2a62/

UPDATE

As of EF 6.0 and later EntityFunctions is replaced by DbFunctions.

Solution 2:

NOTE: at the time of writing this answer, the EF-relation was unclear (that was edited into the question after this was written). For correct approach with EF, check Mandeeps answer.

You can use the DateTime.Date property to perform a date-only comparison.

DateTime a = GetFirstDate();
DateTime b = GetSecondDate();

if (a.Date.Equals(b.Date))
{
    // the dates are equal
}

Solution 3:

I think this could help you.

I made an extension since I have to compare dates in repositories filled with EF data and so .Date was not an option since it is not implemented in LinqToEntities translation.

Here is the code:

        /// <summary>
    /// Check if two dates are same
    /// </summary>
    /// <typeparam name="TElement">Type</typeparam>
    /// <param name="valueSelector">date field</param>
    /// <param name="value">date compared</param>
    /// <returns>bool</returns>
    public Expression<Func<TElement, bool>> IsSameDate<TElement>(Expression<Func<TElement, DateTime>> valueSelector, DateTime value)
    {
        ParameterExpression p = valueSelector.Parameters.Single();

        var antes = Expression.GreaterThanOrEqual(valueSelector.Body, Expression.Constant(value.Date, typeof(DateTime)));

        var despues = Expression.LessThan(valueSelector.Body, Expression.Constant(value.AddDays(1).Date, typeof(DateTime)));

        Expression body = Expression.And(antes, despues);

        return Expression.Lambda<Func<TElement, bool>>(body, p);
    }

then you can use it in this way.

 var today = DateTime.Now;
 var todayPosts = from t in turnos.Where(IsSameDate<Turno>(t => t.MyDate, today))
                                      select t);