Question

I had a test case that looks like this:

[TestMethod]
public void Things_can_be_saved()
{
  var ts = DateTime.Now;
  var thing = new Thing()
  {
      Name = "Some name",
      TimeStamp = ts
  };

  // save it
  var context = new MyDataContext(testDb);
  context.Things.Add(thing);
  context.SaveChanges();

  // pull from a fresh context so we know it's a db pull not cached
  var context2 = new MyDataContext(testDb);
  var fetched = context2.Things.FirstOrDefault(t => t.TimeStamp == ts);

  Assert.AreEqual(thing.Name, fetched.Name); 
}

So, when I run this, I can look in the DB and see ‘thing’ present in the db. I can see that the stored Timestamp column for it is equal to the value in the ts variable at runtime. But ‘fetched’ is null, indicating that EF can’t find it in the FirstOrDefault query. Is there something I’m missing about DateTime equality?

Answer 1

You probably need to change your column in the database to be datetime2 instead of datetime

Also see this thread: DateTime2 vs DateTime in SQL Server