if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[图书丢失_图书编号_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1)
ALTER TABLE [dbo].[图书丢失] DROP CONSTRAINT 图书丢失_图书编号_fk
GO

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK_图书罚款_图书信息]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1)
ALTER TABLE [dbo].[图书罚款] DROP CONSTRAINT FK_图书罚款_图书信息
GO

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[图书归还_图书编号_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1)
ALTER TABLE [dbo].[图书归还] DROP CONSTRAINT 图书归还_图书编号_fk
GO

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[图书借阅_图书编号_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1)
ALTER TABLE [dbo].[图书借阅] DROP CONSTRAINT 图书借阅_图书编号_fk
GO

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK_图书征订_图书信息]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1)
ALTER TABLE [dbo].[图书征订] DROP CONSTRAINT FK_图书征订_图书信息
GO

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[图书注销_图书编号_fk]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1)
ALTER TABLE [dbo].[图书注销] DROP CONSTRAINT 图书注销_图书编号_fk