Database Management Systems...What is Database Normalization? STUDENT(Batch year, Number, Name,...

Database Management

SystemsaProf. Reginald Neil Recario

Institute of Computer Science

University of the Philippines Los Baños

OutlineWe are going to talk about…

Outline

•Data

•Database

•Database Systems

Outline

• Functions and components of a Database Management System

Outline

•Database Normalization

Outline

•Entity Relationship Diagram and Relational Modeling

What is a Data?

What is a Data?

• Facts

• Details of a person (name, home address, etc.)

What is a Database?

What is a Database?

• A collection of logically related data

• Typically visualized as tables

–Column headers

–Rows

What is a Database?Name Degree Program Age

Maria Makiling BS ComputerScience

15

Pedro Penduko BS Statistics 16

Juan Makata BA CommunicationArts

15

What is a Database System?

What is a Database System?

• A database system is simply a database (or databases) with the database management system

What are the functions and components of a Database Management System?

Functions

1.Manipulate data create, retrieve, update and delete

Functions

2.Defining the database metadata

data type, size, and constraints

Functions

3.Process dataperform operations

manipulate data based on an event

Functions

4.Share dataprivileges given to a user

security

Components

A typical DBMS has the following components:

ComponentsInterface

Parser

Query optimizer

Execution engine

Storage

ComponentsInterface

Parser

Query optimizer

Execution engine

Storage

responsible for interacting with the user

ComponentsInterface

Parser

Query optimizer

Execution engine

Storage

checks correctness of syntaxchecks tables and other objects in the query

ComponentsInterface

Parser

Query optimizer

Execution engine

Storage

Simplifies the query for efficient execution

ComponentsInterface

Parser

Query optimizer

Execution engine

Storage

Executes the optimized query

ComponentsInterface

Parser

Query optimizer

Execution engine

Storage

Location where dataand metadata are stored

What is Database Normalization?

What is Database Normalization?• Or simply normalization.

• Reduce or remove redundancy

• Ensure integrity

What is Database Normalization?• Normal forms (NF)

• 1NF, 2NF, 3NF, BCNF, etc.

What is Database Normalization?• 1st Normal form (1NF)

–All attributes within a table/relation must be atomic and single-valued

–Each multivalued attribute must be separated together with the key

What is Database Normalization?STUDENT(Studno, Name, Contact no,

Email address)

Assume a student can have more than one contact number and email address.

What is Database Normalization?Decompose table to satisfy 1NF:

STUDENT(Studno, Name)

STUDENT_CONTACT(Studno, Contact no)

STUDENT_EMAILADDR(Studno, Email address)

What is Database Normalization?Depending on context, attribute Name can still

be broken down to “smaller” attributes:

STUDENT(Studno, Last Name, First Name, Middle Name)

What is Database Normalization?• 2nd Normal form (2NF)

–Attributes of a table/relation must all depend on all keys of the relation

–Functional dependency (FD)

• X → Y

–Full functional dependency

What is Database Normalization?STUDENT(Batch year, Number, Name,

Expected year of graduation)

Batch year is the year of entry (e.g. 2017)

We assume expected year of graduation to be four years.

Batch year and the Number combined is the student number (e.g. 2017-12345)

What is Database Normalization?STUDENT(Batch year, Number, Name,

Expected year of graduation)

FDs:

{Batch year, Number} → {Name}

{Batch year} → {Expected year of graduation}

What is Database Normalization?STUDENT(Batch year, Number, Name)

STUDENT_EXPGRAD(Batch year, Expected year of graduation)

What is Database Normalization?• 3rd Normal form (3NF)

–Attributes within the relation must depend only on a key

–No transitive functional dependency

What is Database Normalization?STUDENT(Studno, Name, Units

earned, Standing)

Units Earned is the number of units earned (taken and passed) by the student

Standing refers to whether the student is a freshman, sophomore, junior or senior based on the earned units.

What is Database Normalization?STUDENT(Studno, Name, Units

earned, Standing)

FDs:

{Studno} → {Name, Units earned, Standing}

{Units earned} → {Standing}

What is Database Normalization?STUDENT(Studno, Name, Units

earned)

STUDENT_STANDING(Units earned, Standing)

On Entity Relationship Diagram and Relational Modeling

On Entity Relationship Diagram and Relational Modeling• Models represent a system

–Notations

–Rules

–Behaviors / processes

On Entity Relationship Diagram and Relational ModelingRelational Model

– A relation (or table) is composed of columns and rows

– Columns → Attributes

– Rows → a record / data

On Entity Relationship Diagram and Relational ModelingRelational Model

Name Degree Program Age

Maria Makiling BS Computer Science 15

Pedro Penduko BS Statistics 16

Juan Makata BA Communication Arts 15

On Entity Relationship Diagram and Relational ModelingEntity Relationship Model

–A high-level conceptual model

–Describes the data as entities having attributes and each entity having relationships with other entities

On Entity Relationship Diagram and Relational ModelingEntity Relationship Diagram

– ERD

–Diagrammatic notation

–Chen’s notation and Crow foot notation

On Entity Relationship Diagram and Relational Modeling

On Entity Relationship Diagram and Relational Modeling

On Entity Relationship Diagram and Relational Modeling

On Entity Relationship Diagram and Relational ModelingExample: An employee is assigned to a room in the

company. An employee has a name, birthday,salary grade and an employee number which isunique. A room has a room number, room size,room capacity, and room location. A roomnumber can identify the room. A number ofemployees can be assigned to a room. Anemployee must be assigned to a room but a roomis not required to be assigned with an employee.An employee can be assigned to only one room.

On Entity Relationship Diagram and Relational Modeling

On Entity Relationship Diagram and Relational ModelingExample: An employee is entitled with some form of

benefits. These benefits often extend to dependents.A dependent of an employee is defined as a either aparent with at age of at least 64 years old or a child ofat most 18 years old. A dependent is described byhis/her name, birthday, relationship to the employeeand highest educational attainment. The employee isdescribed by his/her name, employee no, age anddepartment. The employee no is unique. It is possiblefor an employee to have no dependents. A dependentmust always have an employee to depend on. Adependent depends only to one employee.

On Entity Relationship Diagram and Relational Modeling

End.