When using Linq, is DbNull equivalent to Null?

Question

This is not about DBNull vs Null. I understand the difference.

What I would like to know is if I am using Linq, say to access a User.EmailAddress, then checking User.EmailAddress == null is the same as User.EmailAddress == DBNull correct?

My reasoning is that the absence of data in the database results into Linq not generating an object reference, which then means that null is in fact equivalent to DBNull when used with Linq.

Is my reasoning correct or not?

Answer 1

You shouldn't use DBNull with LinqToSql. The point is Language Integration, and so one concept or name for null will suffice.

Answer 2

Here's the select statement that works in LINQ to SQL for Visual Basic. I assume it will be the same in C#.

User.EmailAdress.Equals(Nothing)

For example:

Dim EmptyEmailAddressEntries = From User in DC.Users _
    Where User.EmailAddress.Equals(Nothing) select User

Will give you all the Users that have nothing in the email address. To check for entries with space " " characters only add

Or

User.EmailAddress = ""