private void detach_Purchases(Purchase entity)
 {
     this.SendPropertyChanging();
     entity.User = null;
 }
 private void attach_Purchases(Purchase entity)
 {
     this.SendPropertyChanging();
     entity.User = this;
 }
 partial void UpdatePurchase(Purchase instance);
 partial void DeletePurchase(Purchase instance);
 partial void InsertPurchase(Purchase instance);