数据库实验

1: if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK_R2_s2]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[R2] DROP CONSTRAINT FK_R2_s2 GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[s2]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [dbo].[s2] GO CREATE TABLE [dbo].[s2] ( [s2no] [char] (6) COLLATE Chinese_PRC_CI_AS NOT NULL , [s2name] [char] (8) COLLATE Chinese_PRC_CI_AS NULL , [sex] [char] (2) COLLATE Chinese_PRC_CI_AS NULL , [birth] [smalldatetime] NULL , [dept] [char] (20) COLLATE Chinese_PRC_CI_AS NULL , [hobby] [char] (30) COLLATE Chinese_PRC_CI_AS NULL ) ON [PRIMARY] GO 2: if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK_R2_c2]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[R2] DROP CONSTRAINT FK_R2_c2 GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[c2]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [dbo].[c2] GO CREATE TABLE [dbo].[c2] ( [c2no] [char] (4) COLLATE Chinese_PRC_CI_AS NOT NULL , [c2name] [char] (20) COLLATE Chinese_PRC_CI_AS NULL , [credit] [int] NULL ) ON [PRIMARY] GO 3: if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[R2]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [dbo].[R2] GO CREATE TABLE [dbo].[R2] ( [s2no] [char] (6) COLLATE Chinese_PRC_CI_AS NOT NULL , [c2no] [char] (4) COLLATE Chinese_PRC_CI_AS NOT NULL , [grade] [tinyint] NULL ) ON [PRIMARY] GO