Database DesignDatabase Development Lifecycle

Database Design: Intro

Database SystemProvides data collection, storage, and retrievalComposed of people, hardware, software, database(s), procedures, and application programs

Database DesignFoundation of a successful database systemShould promote• Data integrity• Prevent data redundancies 반복 & anomalies 오류Must yield a database that• is efficient in its provision of data access.• meet the objectives of the database system and

serves the needs of its users.

Database Design 2

Data Redundancy

Database Systems: Design, Implementation, & Management: Rob & Coronel

Database Design 3

Data Anomaly 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 Design 4

Database Development System Construction

System Analysis• Establish the need and extent of an information systemSystem Development• Design & implement the information system

Database ConstructionPlanning & 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 정비→ (corrective & adaptive) modification, backup & recovery

Database Design 5

Database Development Lifecycle

Planning & Analysis기획분석

Design개념 설계

Implementation구현

Maintenance정비

• Database Objectives

• Business Rules• Data Model

• DBMS Tables• User Interface• SQL Queries

• Modification• Backup & Recovery• Security

Database Design 6

Database Lifecycle: Planning & Analysis

Define Database Objectives 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 7

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→ that can achieve the database objectives

1. Conceptual Design – ER Modeling2. Logical Design – Relational Schema & Normalization3. Physical Design – Schema into DBMS (Table Creation)

What is a Database Model?→ Abstract data structure of the real-world items← Need to understand how business works &

what role data plays

Database Design 8

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 & draw an ER Diagram

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Planning & Analysis Database Design Implement Maintain

Conceptual Design: Business Rules

WhatBrief, precise, and unambiguous descriptions of operations in an organization• Based on policies, procedures, or principles within a specific organization

WhyPromote 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 10

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 data

for optimum information extraction and data manipulation

Why Model?To understand and identify essential data elements

How?Identify Entities 개체, Attributes 속성, & Relationships 관계

STUDENT

TEACHER

ID

GPA

Major

Name

email

Office

Database Design 11

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 12

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 13

Planning & Analysis Database Design Implement Maintain

Database Systems: Design, Implementation, & Management: Rob & Coronel

Database Design: Lifecycle1. Define Database Objectives

What information will the database provide?

2. Examine the Data Environment How does the business work & what data are used?

3. Construct the Data Modela. Enumerate the Business Rule.b. Identify Entities & Relationships between them.c. Define Attributes (and primary & foreign keys) for each entityd. Create an initial E-R diagrame. Normalize the entities 개체 정규화

→ Process for evaluating & designing good table structures

4. Verify the Data Model Does the data model support the database objectives?⇒ If not, modify the Data Model

Database Design 14

Data Model: University Example

Database Design 15

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.

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 17

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 18

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 19

M

M

1

1

ADVISING

1

1

M

M

ENROLL

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