Comparing date parts in LINQ

Try using the Date property of both:

Date today = DateTime.Today; // Effectively DateTime.Now.Date

var dataFromToday = from record in context.Records
                    where record.TimeStamp.Date == today
                    select record;

I believe this works for LINQ to SQL... as tvanfosson says, it doesn't for EF.

• I know that it doesn't. That bit me yesterday. - tvanfosson
• @tvanfosson: Duly made more emphatic :) - Jon Skeet
• A real pain, too, since I typically mock out the data context for unit tests and it does work with LINQ to objects (obviously). I have to remember that when developing the repository that the unit tests can lie about stuff like that. - tvanfosson

Linq to SQL supports translation of the Date property to SQL for comparisons, etc. More information on the supported options can be found on MSDN.

You could create a CLR UDF to do the date only compare and then reference that in your linq to sql linq query.

using System.Data.Entity;

DbFunctions.TruncateTime(u.BirthDate) = DbFunctions.TruncateTime(someDate)

using System.Data.Objects.SqlClient; //Don't forget this!!

//You can access to SQL DatePart function using something like this:

YourTable.Select(t => new { DayOfWeek = SqlFunctions.DatePart("weekday", t.dateTimeField) - 1 }); //Zero based in SQL

//You can compare to SQL DatePart function using something like this:

DateTime dateToCompare = DateTime.Today;
YourTable.Where(t => SqlFunctions.DatePart("weekday", t.dateTimeField) - 1 == dateToCompare }); //Zero based in SQL