接下来，在数据库里(开始菜单-?程序-? microsoft SQL server-?查询分析器)，数据库——系统数据库——master——表——右键，刷新， 就出来了新建的表。如下图。 四．实验结果 CDM图（ER图）：

PDM图：

SQL代码： if exists (select 1 from sysobjects where id = object_id('Library') and type = 'U') drop table Library go if exists (select 1 from sysobjects where id = object_id('Unit') and type = 'U') drop table Unit go if exists (select 1 from sysobjects where id = object_id('book') and type = 'U') drop table book go if exists (select 1 from sysobjects where id = object_id('reader') and type = 'U') drop table reader go if exists (select 1 from sysobjects where id = object_id('\ and type = 'U') drop table \go /*==============================================================*/ /* Table: Library */ /*==============================================================*/ create table Library ( Library_No char(20) not null, Library_Address varchar(38) not null, constraint PK_LIBRARY primary key nonclustered (Library_No) )