软件双语Lecture32011春.pptVIP

第3讲 数据库系统结构(难点)  Database System Architecture Instructor：孙瑜 Department:计算机科学学院计算机专业教研室 Email：bobsunyu@ QQ：782061453 QQ答疑群 Review:Data Models Data Model: A set of concepts to describe the structure of a database, the operations for manipulating these structures, and certain constraints that the database should obey. Data Model Structure and Constraints: Constructs(构造) are used to define the database structure Constructs typically include elements (and their data types) as well as groups of elements (e.g. entity, record, table), and relationships among such groups Constraints specify some restrictions on valid data; these constraints must be enforced(强制) at all times Review:Data Models (continued) Data Model Operations: These operations are used for specifying database retrievals(获取) and updates by referring to the constructs of the data model. Operations on the data model may include basic model operations (e.g. generic insert, delete, update) and user-defined operations (e.g. compute_student_gpa, update_inventory) Review:Categories of Data Models Conceptual (high-level, semantic) data models: Provide concepts that are close to the way many users perceive data. Entity-Relationship Model Physical (low-level, internal) data models: Provide concepts that describe details of how data is stored in the computer. Implementation (representational,logical) data models: Provide concepts that fall between the above two, and may be understood by end users but that are not too far removed from the way data is organized within the computer. Relational, network, hierarchical 课程教材的架构 数据库基本概念(Introduction) Chapter 1: Introduction 补充：Data Model 补充：Database System Architecture(本讲内容) 关系数据模型(逻辑模型之一：Relational Model) Chapter 2.1-2.4:The Relational Model(“数据结构”和“数据的约束条件”) Chapter 2.5-2.8:Relational Algebra(“数据操作”) Chapter 3:Basic SQL Query Language (“数据操作”) Chapter 5:Programs to Access a Database (“数据操作”) 数据库设计 Chapter 6: Database Design Chapter 8: Indexing(物理数据库设计) 本讲主要内容