How do I perform Date Comparison in EF query?

Question

Please help. I am trying to figure out how to use DATE or DATETIME for comparison in a linq query.

Example: If I wanted all Employee names for those who started befo

Answer 1

You can check the condition like this

var nextDay = DateTime.Today.AddDays(1);

var query = from e in db.MyTable
            where e.AsOfDate >= DateTime.Today && e.AsOfDate < nextDay 
            select e;

here you'll get the records on AsOfDate date as we checking between today(00:00:00) and tommorow(00:00:00) we'll get today's date record only what ever may be the time...

Answer 2

I am using a LinqDataSource and I had problems getting my query with a Date Comparison in it to execute without errors. The answer is to use the WhereAddParameters function and add the test value as a strongly typed parameter.

See the example below where I am matching a groupid and checking to see if the StopDate in my record is greater that or equal to a Date/Time stamp of now.

I am using this code fragment currently and it works like a charm.

LinqCampaigns.WhereParameters.Add("StopDate", System.Data.DbType.Date, DateTime.Now.ToString())
LinqCampaigns.Where = "GroupId = " & myGrp & " &&  " & "StopDate >= @StopDate"

Works like a charm....

Answer 3

Use the class DbFunctions for trimming the time portion.

using System.Data.Entity;

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

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

Answer 4

use a local variable to store the Date value and then use that variable in the query:

DateTime today = DateTime.Now.Date; from scheme in context.schemes where scheme.EndDate > today select scheme

Answer 5

ensure that you check null value like this :

 '(from mm in _db.Calls 
   where mm.Professionnal.ID.Equals(proid)
   && mm.ComposedDate.HasValue &&
   (mm.ComposedDate.Value >= datemin) && (mm.ComposedDate.Value <= date)
   select mm).ToArray();'