if not exists (select * from sys.syscolumns where name = 'IsPrivate' AND id = object_id(N'dbo.ConnectionLog'))
    alter table dbo.ConnectionLog
    add IsPrivate bit not null constraint DF_ConnectionLog_IsPrivate DEFAULT(0)
        ,PrivateUserID uniqueidentifier null constraint FK_ConnectionLog_PrivateUserID FOREIGN KEY REFERENCES dbo.UserInfo(ID)