if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[圖書丟失_圖書編號_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1)
ALTER TABLE [dbo].[圖書丟失] DROP CONSTRAINT 圖書丟失_圖書編號_fk
GO

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK_圖書罰款_圖書信息]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1)
ALTER TABLE [dbo].[圖書罰款] DROP CONSTRAINT FK_圖書罰款_圖書信息
GO

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[圖書歸還_圖書編號_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1)
ALTER TABLE [dbo].[圖書歸還] DROP CONSTRAINT 圖書歸還_圖書編號_fk
GO

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[圖書借閱_圖書編號_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1)
ALTER TABLE [dbo].[圖書借閱] DROP CONSTRAINT 圖書借閱_圖書編號_fk
GO

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK_圖書征訂_圖書信息]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1)
ALTER TABLE [dbo].[圖書征訂] DROP CONSTRAINT FK_圖書征訂_圖書信息
GO

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[圖書注銷_圖書編號_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1)
ALTER TABLE [dbo].[圖書注銷] DROP CONSTRAINT 圖書注銷_圖書編號_fk