Update a single property of a record in Entity Framework Code First

Question

How can I update a single property of a record without retrieving it first? I\'m asking in the context of EF Code First 4.1

Says I have a class User

Answer 1

You can try a sort of hack:
context.Database.ExecuteSqlCommand("update [dbo].[Users] set [LastActivity] = @p1 where [Id] = @p2",
new System.Data.SqlClient.SqlParameter("p1", DateTime.Now),
new System.Data.SqlClient.SqlParameter("p2", id));