private void detach_Attachment(Attachment entity)
 {
     this.SendPropertyChanging();
     entity.Items = null;
 }
 private void attach_Attachment(Attachment entity)
 {
     this.SendPropertyChanging();
     entity.Items = this;
 }
 partial void UpdateAttachment(Attachment instance);
 partial void DeleteAttachment(Attachment instance);
 partial void InsertAttachment(Attachment instance);