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Database Design
Database Development Lifecycle
Why Database? From Data …
Simple dumping of data on the storage medium provides little value.
Database System 2
id name address country pay due100 J. Rodney 12 High Rd., Leeds UK 33.75
523 E. Hoover 52 Ln. Muncie, IN USA 0
800 M. Old Box. 9, Miami, FL USA 12.50
product_id title cost sale price123-19-20 Joy of Living 12.50 19.25
169-15-34 Learning Judo 20.00 25.00
354-90-33 Your Dream Home 18.25 24.25
PRODUCT
CUSTOMER
SALE
id zone product_id quantity total price100 UK 123-19-20 2 38.50
523 USMW 354-90-33 1 24.25
100 UK 169-15-34 1 25.00
800 USSE 123-19-20 1 19.25
The goal is not just storage of data, but ultimately the extraction of information to support decision making by key people and groups in the organization. Data Information (e.g. reports, tabulations, graphs) Decisions
Sales of Titles in the UK Zone
0
10
20
30
40
50
Joy of Living Learning Judo
Titles
To
tal S
ale
s (
$)
Database System 3
- Summarized fact or information -
* In the UK ZONE, Joy of Living had a sale of
$38.50, and Learning Judo had a sale of $25.
** UK ZONE had the total sale of $63.50, USMW
had $24.25, and USSE had $19.25.
Title UK USMW USSE total
Joy of Living 38.50 19.25 57.75
Learning Judo 25.00 25.00
Your Dream Home 24.25 24.25
63.50 24.25 19.25 107.00
SALE by Zone**
*
Why Database? … Towards Information
Database System 4
Database Systems: Design, Implementation, & Management: Rob & Coronel
(DBMS)
Why Database? … For Decision Making
Database Design: Intro
Database SystemProvides data collection 수집, storage 저장, and retrieval 검색
Composed of people, hardware, software, database(s), procedures, and application programs
Database DesignFoundation of a successful database system 휼륭한 DB system의 기반
Should promote
• Data integrity 데이터 무결성
• Prevent data redundancies 반복 & anomalies 오류
Must yield a database that
• is efficient in its provision of data access 효율적인 데이터 접근
• meet the objectives of the database system and serves the needs of its users DB시스템의 목적과 이용자의 요구 만족
Database Design 5
Data Redundancy (데이터의반복성)
Database Systems: Design, Implementation, & Management: Rob & Coronel
Database Design 6
Data Anomaly 데이터의오류
Database System 7
Update anomalies 수정오류
- Data inconsistencies resulting from “islands of information” problem
Insertion Anomalies 삽입오류
- Creation of bogus record when adding new data (e.g. new agent)
Deletion Anomalies 삭제오류
- Unintended deletion of related data (e.g. agent data when deleting customer)
Database Systems: Design, Implementation, & Management: Rob & Coronel
Database Development System Construction 시스템 구축
System Analysis 시스템 분석
• Establish the need and extent of an information system
System Development 시스템 개발
• Design & implement the information system
Database Construction DB 구축
Planning & Analysis 기획분석
Analyze data environment & Define database objectives
Database Development
• Design 설계
→ Construct a data model & establish data management processes
• Implementation 구현
→ Create the storage structure (e.g., tables) & user interface for data management
• Maintenance 유지보수
→ (corrective & adaptive) modification, backup & recovery
Database Design 8
Database Development Lifecycle
Planning & Analysis
기획분석
Design
개념 설계
Implementation
구현
Maintenance
정비
Database Objectives
Business Rules Data Model
DBMS Tables User Interface SQL Queries
Modification Backup & Recovery Security
Database Design 9
Database Lifecycle: Planning & Analysis
Define Database Objectives DB목적설정
What will the database (DB) do? What tasks 업무/작업will the DB support?
→ Data Entry, Update, Search
What information will the DB provide?→ Q & A
← Study the DB environment
How does the business operate?
Who are the players?
How does the information flow?
← Examine the data
Database Design 10
Planning & Analysis Database Design Implement Maintain
Sample Q&A: Recipe Database
Query Result
recipe name recipe info (ingredients, steps, …)
ingredients
recipe names recipe info
main ingredient (meat, fish, …)
recipe type (diet, diabetic, …)
recipe category (soup, desert, …)
budget, time
Database Lifecycle: Database Design
Create a Database Model DB 모델 제작
→ that can achieve the database objectives
1. Conceptual Design – ER Modeling
2. Logical Design – Relational Schema & Normalization
3. Physical Design – Schema into DBMS (Table Creation)
What is a Database Model?
→ Abstract data structure of the real-world items
실제 항목의 추상적인 data 구조
← Need to understand how business works & what role data plays
Database Design 11
Planning & Analysis Database Design Implement Maintain
Database Design: Conceptual Design
Conceptual Design Steps1. Enumerate the Business Rules
How does the business work?
2. Construct the Data Model Identify Entities, Relationship, Attributes & draw an ER Diagram
3. Verify the Data Model Does the data model support the fulfillment of database objectives?
Database Design 12
Planning & Analysis Database Design Implement Maintain
Conceptual Design: Business Rules
What 조직 내 정확한 업무 기술
Brief, precise, and unambiguous descriptions of operations in an organization• Based on policies, procedures, or principles within a specific organization
Why 정확한 data model 설계를 위하여
Promote creation of an accurate data model← Enhance understanding & facilitate communication
How (sources)Interviews, Documentation, Observation
Examples
• A painter can draw many paintings. A painting is drawn by a single painter.
• A teacher can teach 0 to 6 courses per semester.• A course is taught by a single teacher.
• A student must take at least 1 and at most 6 courses.• A course can have 10 to 40 students.
PAINTER PAINTINGdraws1 M
TEACHER COURSEteaches1 M
STUDENT
takes
M
N
Database Design 13
Planning & Analysis Database Design Implement Maintain
Conceptual Design: Data Modeling
What is Data Modeling?A model is a representation of reality
that retains only carefully selected essential details.
Logical organization of datafor optimum information extraction and data manipulation
Why Model? 주요한 data 요소들을 이해하고 인식하기 위하여
To understand and identify essential data elements
How?Identify Entities 개체, Attributes 속성, & Relationships 관계
STUDENT
TEACHER
ID
GPA
Major
Name
Office
Database Design 14
Planning & Analysis Database Design Implement Maintain
Database Design: Relational Schema
Specification of the overall structure/organization of a database
Relations Entities w/ Attributes
Primary key• Unique identifier
Foreign key PK of related table
Relationship type (connectivity) 1:M, M:N, 1:1
Database Design 15
Planning & Analysis Database Design Implement Maintain
https://www.coursera.org/learn/analytics-mysql/lecture/hDLIS/relational-schemas
Database Design: Data Dictionary
Detailed description of a data model Lists attribute names and characteristics for each table in the database Blueprint & documentation of a database
Database Design 16
Planning & Analysis Database Design Implement Maintain
Database Systems: Design, Implementation, & Management: Rob & Coronel
Database Design: Lifecycle
1. Define Database Objectives DB 목적 설정
What information will the database provide?
2. Examine the Data Environment data 환경 조사
How does the business work & what data are used?
3. Construct the Data Model data모델 구축
a. Enumerate the Business Rule.
b. Identify Entities & Relationships between them.
c. Define Attributes (and primary & foreign keys) for each entity
d. Create an initial E-R diagram
e. Normalize the entities 개체 정규화
Process for evaluating & designing good table structures
4. Verify the Data Model data모델 확인
Does the data model support the database objectives?
If not, modify the Data Model
Database Design 17
Data Model: University Example
Database Design 18
Appendix
Database System 19
DB Design - Conceptual Design: Data Analysis & Requirements
Discover the data that can be transformed into desired information Information Need
What kind of information is needed?→ what output (queries & reports) must be generated by the system?
User Characteristics Who will use the information? How will information be used?
Information Source Where is the information to be found? How is the information to be extracted?
Information Constitution What data elements are needed to produce the information? What are the data attributes and relationships? What data transformations are to be used to produce the information?
Develop a thorough understanding of the company’s data Flow, uses, characteristics
Data Flow Diagram
Data sources Interviews, direct observation Business Rules
Narrative description of policy & procedures
Database System 20
Planning & Analysis Database Design Implement Maintain
Conceptual Design – ER Modeling: Business Rules What: Brief, precise, and unambiguous descriptions of operations in an organization
• based on policies, procedures, or principles within a specific organization• help to create and enforce actions within that organization’s environment• apply to any organization that stores and uses data to generate information
Why: Enhance understanding & facilitate communication• Standardize company’s view of data• Constitute a communications tool between users and designers • Allow designer to understand business process as well as the nature, role, and scope of data
Promote creation of an accurate data model
How (sources)Interviews• Company managers, Policy makers, Department managers, End users
Written documentation• Procedures, Standards, Operations manuals
Observation• Business operations
Examples• A painter can draw many paintings. A painting is drawn by a single painter.• A teacher can teach 0 to 6 courses per semester. A student must take at least 1 and at most 6
courses.
Database System 21
Planning & Analysis Database Design Implement Maintain
E-R model is verified against proposed system processes.
Corroboration that intended processes can be supported by the database model
Careful reevaluation of the entities and detailed examination of attributes
Verification of business transactions as well as system and user requirements
May reveal additional entity and attribute details.
Verification process is iterative.1. identify ER model’s central entity
2. identify modules/subsystems & components
3. identify transaction requirements update/insert/delete/query/report
user interface
4. verify all processes against ER model
5. make necessary changes
6. repeat steps 2 through 5
Database System 22
Database Systems: Design, Implementation, & Management: Rob & Coronel
Conceptual Design – ER Modeling: E-R Model Verification
Planning & Analysis Database Design Implement Maintain
What are the advantages & disadvantages?Cost• purchase, maintenance, operational, training, etc.
Features & Tools• ease-of-use, performance, DB administration, etc.
• application development tools
DB model• hierarchical, RDB, Object-oriented, etc.
Portability• platform, O/S, SQL
Hardware requirement• processor, RAM
Database System 23
DB Design - Conceptual Design: DBMS Selection
Planning & Analysis Database Design Implement Maintain
Logical DesignTranslate conceptual design into internal model that maps objects in model to specific DBMS constructs• From software independent to software dependent
Detailed & functional descriptions of system components• Specify system processes and I/O.
• e.g., table design, attribute definitions, access restrictions
Physical DesignSelect the data storage and data access characteristics of the database• More important in older hierarchical and network models
• Becomes more complex when data are distributed at different locations
Can affect the database performance• e.g. storage media, buffer size, etc.
Designers favor software that hides physical details
Database System 24
DB Design: Logical & Physical Design
Planning & Analysis Database Design Implement Maintain
DB Lifecycle - Analysis: Feasibility Analysis
Technological FeasibilityWhat hardware, software, and additional resources would be needed?
What is available in-house? What has to be purchased?
How will the new system be integrated?
Operational FeasibilityWho will design the system?
Who will maintain the system?
Who will do training or help-desk support?
Can the available personnel provide the time? New personnel necessary?
Economic FeasibilityExpected cost of the overall project ($)?• Software, hardware, application development, staff-time
• Hidden cost (unforeseen)
Other costs• What is the competition/comparable unit doing?
• Would data sharing among departments lead to additional expenses?
Benefits • How soon expected?
Database System 25
Planning & Analysis Database Design Implement Maintain
DB Lifecycle - Design: Data Modeling
What is Data Modeling?A model is a representation of reality that retains only carefully selected essential details.
Logical organization of data for optimum information extraction and data manipulation
Why Model?To understand and identify essential data elements
To produce a representation that can be transformed into a schema
How?Data modeling involves• identifying entities, attributes, and relationships
Database System 26
Planning & Analysis Database Design Implement Maintain
Exercises
BBB
AAA BBBdoesM N
one AAA does many BBB
one BBB is done by many AAA
CCC has1 M
a CCC has several BBB
each BBB belongs to one CCC
a, an, each one 1
some, several many M
DDD AAAowns1 1
a DDD owns one AAA
each AAA is owned by one DDD
does
M
N
ERD Tips
CLASS
PROFESSOR STUDENTteachesM N
A professor teaches many students.
A student is taught by several professors.
PROFESSOR teaches1 M
A professor teaches many classes.
A class is taught by a single professor.
STUDENT CLASSenrollsM N
A students enrolls in many classes.
A class has many students.
enrollsMN
STUDENT
ERD example
PROFESSOR STUDENTteachesM N
PROFESSOR CLASS STUDENTteaches has
Crow’s Foot ERD
PROFESSOR CLASS STUDENT
Chen ERD
teaches has1 NM M
ERD example
PROFESSOR CLASS STUDENTteaches has1 NM M
Business Rules
A professor can teach many classes. A class is taught by one
professor.
A student can take many classes. A class can have many students.
A course can generate many classes. A class is generated by one
course.
COURSE
generates
1
M
ERD Example
1. Draw an E-R Diagram of the data model described by the business rules below.
One region can be the location for many stores. Each store is located in only one region.
Each store employs one or more employees. Each employee is employed by one store.
A job can be assigned to many employees.-- e.g., The "Sales Representative" job can be assigned to more than one employee at a time.
Each employee can have only one job assignment.
Data Modeling Exercises
1. Draw an E-R Diagram of the data model described by the business rules below.
One region can be the location for many stores. Each store is located in only one region.
Each store employs one or more employees. Each employee is employed by one store.
A job can be assigned to many employees.-- e.g., The "Sales Representative" job can be assigned to more than one employee at a time.
Each employee can have only one job assignment.
1. Draw an E-R Diagram of the data model described by the business rules below.
One region can be the location for many stores. Each store is located in only one region.
Each store employs one or more employees. Each employee is employed by one store.
A job can be assigned to many employees.-- e.g., The "Sales Representative" job can be assigned to more than one employee at a time.
Each employee can have only one job assignment.
REGION
EMPLOYEEemployees
M
is location for
STORE
M1
1
JOB
1
M
is assigned to
Database Design 32
2. Identify the business rules and draw an E-R diagram of the situation described below.
For each professor, there may be multiple advisees. A professor teaches many classes and a class is taught by one professor.
Data Modeling Exercises
PROFESSOR CLASSteaches
advises
STUDENT
M
1
1
M
Business Rules
A professor can advise many students.
A student is advised by one professor.
A professor can teach many classes.
A class is taught by one professor
Database Design 33
3. Create a data model (i.e. ERD) for the school database described below.
DB will keep track of advising and class information. DB should provide following information.
- The list of students advised for a given year & dates of advising sessions for each students
- Course listing for each year & student grades for each class
Data Modeling Exercises
PROFESSOR CLASSteaches
advises
STUDENT
M
1
1
M
Business Rules
A professor can advise many students. A student is advised by one professor.
A professor can teach many classes. A class is taught by one professor.
A student can take many classes. A class can have many students.
A course can generate many classes. A class is generated by one course.
A professor can meet many times with an advisee. A student can meet many times with the advisor.
COURSE
takes
3. Create a data model (i.e. ERD) for the school database described below.
DB will keep track of advising and class information. DB should provide following information.
- The list of students advised for a given year & dates of advising sessions for each students
- Course listing for each year & student grades for each class
generates
1
M
3. Create a data model (i.e. ERD) for the school database described below.
DB will keep track of advising and class information. DB should provide following information.
- The list of students advised for a given year & dates of advising sessions for each students
- Course listing for each year & student grades for each class
Database Design 34
M
M
1
1
ADVISING
1
1
M
M
3. Create a data model (i.e. ERD) for the school database described below.
DB will keep track of advising and class information. DB should provide following information.
- The list of students advised for a given year & dates of advising sessions for each students
- Course listing for each year & student grades for each class
M
N
Sample DB
ENROLL