库数据库的ER图和SQLDDL_Sql_Database Design_Entity Relationship_Er Diagrams

库数据库的ER图和SQLDDL

sql database-design

库数据库的ER图和SQLDDL,sql,database-design,entity-relationship,er-diagrams,Sql,Database Design,Entity Relationship,Er Diagrams,我试图为一个简单的库数据库绘制一个ER图和SQLDDL 我拥有以下实体： Book (holds the ISBN as key, book title, author) Copy (copyID of a copy of a book, dateAcquired, dateDestroyed) Member (MemberID, name, address) Loaned (i guess the date due and the date back and obviously foreign

我试图为一个简单的库数据库绘制一个ER图和SQLDDL

我拥有以下实体：

Book (holds the ISBN as key, book title, author)
Copy (copyID of a copy of a book, dateAcquired, dateDestroyed)
Member (MemberID, name, address)
Loaned (i guess the date due and the date back and obviously foreign keys for memberID and copyID)

成员也可以是学生或职员。所以我认为这应该是一种“是-是”的关系

如何在适当的ER图和SQL-DDL中表示这一点

我使用SQL Server 2008 Express为Northwind db创建了此图。该图由SSMS绘制

遵循以下步骤

在SSMS中展开数据库

右键单击数据库关系图

选择新数据库关系图

在“添加表格”对话框中选择表格图表将被创建并显示在窗口中。可以在图表窗口中创建新的表、关系、索引等对于SQL-DDL，我使用SSMS编写dataabse脚本