Question

I have a guid? field in my POCO and when I create a new entry in my DB and look at it through SSMSE, I see NULL in that field. After choosing a manager for this new user entry, the guid? field is updated to hold the id of the new manager. However, if I want to change the user back to having no manager, how can I set the field back to NULL?

Should I be using Guid instead of Guid? and write Guid.Empty to the DB instead?

Answer 1

Should I be using Guid instead of Guid? and write Guid.Empty to the DB instead?

Not really. You could do that, but you wouldn’t really gain much. Semantically, if there is “no” value for a field, NULL is the correct value. What you are talking about is using a magic value.

how can I set the field back to NULL?

Set the Guid? to null on your POCO. For example, if your POCO looks something like this:

public class Poco
{
    public Guid? Manager { get; set; }
}

Set it to null like this:

somepocoinstance.Manager = null;

Then commit the changes.