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chapter 1. Introduction to Database System

Database Systems

 

DBMS: database management system

 

Topics on database systems:

  • DB systems concepts
  • realtional  model
  • SQL
  • E-R model
  • DB design(RDB design)
  • storage and file structure
  • indexing
  • Query Processing & Optimization
  • Transaction
  • Concurrency Control
  • Recovery

 

Database Systems & DB design

 

Drawbacks of using file systems to store data:

  • Data redundancy and inconsistency
  • Difficulty in accessing data
  • Data isolation
  • Integrity problems
  • Atomicity of updates 
  • Concurrent access by multiple users
  • Security problems
  • Data Dependence Problem

 

View of Data

  • View level: describes only part of the entire database. Views can also hide information for security purpose
  • Logical leve: describe what data stored in database, and what relationship among the data
  • Physical level: describe how data are actually stored

 

DB language

  • DDL(Data definition language)

Data dictionary contains metadata: database schema、Integrity constrains、Authorization

  • DML(Data manipulation language) 操控

DML also konown as query language

Two classes of languages: Procedural、Declarative 

SQL is the most widely used query language

  • DCL

 

Query Processing: Parsing and translation、Optimization、Evalation

 

Query Processing Procedure: