ToString conversion in the C# LINQ query

Question

I am having (most likely a trivial problem) with the strings comparison in C#

I am running this LINQ query

var result = from q in Table
             where q.ValueDate.ToString() == "12/11/2014 12:00:00 AM"
             select q;

and get an empty response

However, when I try

foreach (var i in Table)
{
    Console.WriteLine(i.ValueDate.ToString());
}

I get

12/11/2014 12:00:00 AM
12/11/2014 12:00:00 AM
12/11/2014 12:00:00 AM
12/11/2014 12:00:00 AM

What am I doing wrong here?

Answer 1

I wouldn't sacrifice the type safety of a Date by converting it to a string - what is possibly happening is that the ToString() is being converted to a *Char type via CAST / CONVERT in the DB, which results in a different format. Here's how I would do it:

var checkDateTime = new DateTime(2014, 11, 12);
var result = from q in Table
          where q.ValueDate == checkDateTime
          select q;

Answer 2

You can use DateTime object instead of doing string Comparisons:

DateTime filter = new DateTime(2014,12,11);
var result = from q in Table
              where q.ValueDate == filter)
              select q

or try specifying your date format:

var result = from q in Table
              where q.ValueDate.ToString("dd/MM/yyyy hh:mm:ss tt") == "12/11/2014 12:00:00 AM"
              select q;

See Attached Fiddle Example