use Envisage
go
if exists(select * from sys.columns 
	where Name = N'PreferredResourceAllocation' and Object_ID = Object_ID(N'AspNetUsers'))
	set noexec on
begin transaction
		ALTER TABLE [dbo].[AspNetUsers] ADD [PreferredResourceAllocation] [bit] NULL
		go
		UPDATE [dbo].[AspNetUsers] SET [PreferredResourceAllocation]=0 WHERE [PreferredResourceAllocation] IS NULL
		go
		ALTER TABLE [dbo].[AspNetUsers] ADD  CONSTRAINT [DF_AspNetUsers_PreferredResourceAllocation]  DEFAULT ((0)) FOR [PreferredResourceAllocation]
		go
		ALTER TABLE [dbo].[AspNetUsers] ALTER COLUMN [PreferredResourceAllocation] [bit] NOT NULL

commit transaction