DateTime "null" value

For normal DateTimes, if you don't initialize them at all then they will match DateTime.MinValue, because it is a value type rather than a reference type.

You can also use a nullable DateTime, like this:

DateTime? MyNullableDate;

Or the longer form:

Nullable<DateTime> MyNullableDate;

And, finally, there's a built in way to reference the default of any type. This returns null for reference types, but for our DateTime example it will return the same as DateTime.MinValue:

default(DateTime)

or, in more recent versions of C#,

default

If you're using .NET 2.0 (or later) you can use the nullable type:

DateTime? dt = null;

or

Nullable<DateTime> dt = null;

then later:

dt = new DateTime();

And you can check the value with:

if (dt.HasValue)
{
  // Do something with dt.Value
}

Or you can use it like:

DateTime dt2 = dt ?? DateTime.MinValue;

You can read more here:
http://msdn.microsoft.com/en-us/library/b3h38hb0.aspx

I'd consider using a nullable types.

DateTime? myDate instead of DateTime myDate.

You can set the DateTime to Nullable. By default DateTime is not nullable. You can make it nullable in a couple of ways. Using a question mark after the type DateTime? myTime or using the generic style Nullable.

DateTime? nullDate = null;

or

DateTime? nullDate;

You can use a nullable class.

DateTime? date = new DateTime?();

You can use a nullable DateTime for this.

Nullable<DateTime> myDateTime;

or the same thing written like this:

DateTime? myDateTime;

I always set the time to DateTime.MinValue. This way I do not get any NullErrorException and I can compare it to a date that I know isn't set.

The question itself answers it the proper way. "How do you deal with datetime if it is null?" and questioner gives the answer at the end with DateTime.MinValue. My thought is that questioner's approach should be the way with little change. I would recommend using DateTime.MaxValue to compare since it wont happen until 12/31/9999. If true then show field as something else other than a date. Here is the example;

 DateNotified = DBNull.Value.Equals(reader["DateNotified"])? Convert.ToDateTime(reader["DateNotified"]): DateTime.MaxValue

and on the front end if it is Grid you are using then;

columns.Add(col => col.DateNotified).Css("text-right").Titled("Date Notified").RenderValueAs(c => c.DateNotified.ToString("MM/dd/yyyy").Equals(DateTime.MaxValue) ? "":c.DateNotified.ToString("MM/dd/yyyy"));

or if a simple view then

@Model.DateNotified.ToString("MM/dd/yyyy").Equals(DateTime.MaxValue) ? "":Model.DateNotified.ToString("MM/dd/yyyy")