Transcript 슬라이드 1

Ch. 1
데이터베이스시스템
What to Learn
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Database System Overview
Entity-Relationship diagram
Relational Data Model
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How to use Commercial DBMS’s
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Structure & Constraints
SQL language
MS Access
MS SQL Server
Normalization (정규화)
Transaction & Concurrency (동시성)
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What to Learn
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Database and Database system
Modeling a real world
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Conceptual Modeling
Data Modeling
Data Structuring
File processing system
Advantages of database system
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What is a database (1)
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data
numbers, characters, images or other outputs from
devices to convert physical quantities into symbols,
in a very broad sense
현실세계의 사물과 사건을 문자, 수치, 기호, 음성, 그
림 등의 형태로 표현한 기록 (record)
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information
the result of processing, manipulating and
organizing data in a way that adds to the
knowledge of the person receiving it.
사용자에게 전달되어 의사결정 등에 유용하게 쓰이도
록 가치 있는 형태로 변환된 뜻(meaning,
interpretation)
Information = Processing (Data)
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What is a database (2)
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database
a collection of persistent data that is used by the
application systems of some given enterprise
체계적으로 저장되고 통합적으로 관리되는 데이터의
집합 (collection)
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Textbook definition (p.13)
조직체의 응용시스템들이 공유해서 사용하는 운영데
이터(operational data)들이 구조적으로 통합된 모임
(operational data means data from day-to-day
operations. In these days we store all the
necessary data in the database including decision
support database, not just operational data)
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Database system
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Database system
computerized record–keeping system
a computerized system whose overall purpose is to
store information and to allow users to retrieve and
update that information on demand.
데이터베이스 개념과 기술에 입각하여 데이터를 수집/저
장/가공/제공하는 컴퓨터 응용시스템
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Database Management System (DBMS)
A component of a database system
Software that handles all access to the database
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Database system
Information
Processing
Users
DBMS
Computer
Database
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Modeling of the Real World
Real
World
conceptual
system boundary modeling
E-R
diagram
data
modeling
conceptual
world
logical schema
data
structuring
physical schema
computer
world
stored database
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Conceptual modeling
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System boundary
only the data we are interested
in
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Entity
any distinguishable object that
is to be represented in the
database
e.g. book, student, department
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Relationship
an association among entities
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E-R diagram
Publisher
publish
loan
Book
title
purchase
Seller
author
ISBN
belong
loan date
return date
purchase date
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Student
Department
Attributes (properties 속성)
Items we describe (express) entities or relationships with
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From the view of a database, entities and
relationships are the same
both of them are represented as tables
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Data Modeling
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Data model
an abstract, self-contained,
logical definition of the objects,
operators, constraints, and so
forth, that together constitute
the abstract machine
가상의 컴퓨터에서 데이터 객체들
의 구조, 연산, 제약조건들을 명시
한 정의
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Data models differ in
structure, operators, constraints
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hierarchical data model (p.35)
회사
부서1
프로젝트1
사원1
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부서1
프로젝트2
사원2
사원3
프로젝트3
사원4
사원5
pre-relational, tree-structure, use pointers
a node has only one parent node
What if an employee works for two projects
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network data model (p.36)
대학
학과1
과목1
학생1
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학과2
과목2
학생2
학생3
과목3
학생4
학생5
pre-relational, use pointers
a node can have more than one parent node
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relational data model
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Student table
NAME
송치윤
김구완
최재석
조미림
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ST_NO
52015
53116
56034
52042
ADDRESS
DEPT
GRADE
사당동
컴퓨터
3.3
홍제동
정보통신
3.1
양재동
정보관리
3.5
역삼동
컴퓨터
2.9
The data is perceived by the user as tables (and nothing
but tables)
데이터베이스의 논리적 구조가 relation 즉, 테이블의 집합으로 표현
되는 데이터 모델
relation is a mathematical term for a table
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Other data model
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Object-oriented data model
from the OOP (object oriented programming)
use pointers
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Object/Relational data model
hybrid of OODB & RDB
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Data Structuring
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Ch.1 Database System
Physical representation of
data
Consider file structure
indexing
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file processing system
vs. database system
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What is file processing system
Which is easier to use?
Problems of file processing system
1. data incompatiblity
2. data redundancy
3. data dependency
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example of problems
Product1 (Prod_No, Prod_Name, price,
monthlysales)
Product2 (Prod_No, Prod_Name, cost,
monthlyproduction)
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Product1 is sorted by Prod_No, while Product2 is
sorted by Prod_Name
Sales department & production department use
different names for the same product.
Prod_Name’s are used twice
If the cost is inserted in Product1, application
program that used Product1 should be changed.
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Data in the database system
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Shared by multi-users
Integrated in a single database
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Above characteristic requires
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Standardization (표준화)
Concurrency control (동시성 제어)
Integrity (무결성)
Security (보안성)
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Advantages of database systems
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The data can be shared
Redundancy and Incompatibility can be
reduced
Transaction support can be provided
(Transaction Commit or Rollback)
Integrity can be maintained
Security can be enforced
Standards can be enforced
Conflicting requirements can be balanced
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