This document provides an overview of key database concepts including: - The components of a database including fields, records, files and how they relate to tables and rows in a DBMS. - Entity-Relationship modeling and the three basic relationship types. - The normalization process which determines required tables and columns to reduce redundancy. - How tables can be linked through primary and foreign keys. - Structured Query Language (SQL) which is used to interact with database tables.

1. Overview of Database Concepts

2. Chapter Objectives
• Identify the purpose of a database
management system (DBMS)
• Distinguish a field from a record and a
column from a row
• Identify the basic components of an Entity-
Relationship Model
• Define the three types of relationships that
can exist between entities

3. Chapter Objectives
• Identify the problem associated with many-
to-many relationships and the appropriate
solutions
• Explain the purpose of normalization
• Describe the role of a primary key
• Identify partial dependency and transitive
dependency in the normalization process

4. Chapter Objectives
• Explain the purpose of a foreign key
• Determine how to link data in different
tables through the use of a common field
• Explain the purpose of a structured query
language (SQL)

5. Database Terminology
• Database – logical structure to store
data
• Database Management System
(DBMS) – software used to create
and interact with the database

6. Database Components
• Character
• Field
• Record
• File

7. Database Components -
Character
• Basic unit of data
• Can be a letter, number, or special symbol

8. Database Components - Field
• A group of related characters
• Represents an attribute or characteristic of
an entity
• Corresponds to a column in the physical
database

9. Database Components - Record
• A collection of fields for one specific entity
• Corresponds to a row in the physical
database

10. Database Components - File
• A group of records about the same type of
entity

11. Components Example

12. Review of Database Design
• Systems Development Life Cycle (SDLC)
• Entity-Relationship Model (E-R Model)
• Normalization

13. Systems Development Life Cycle
(SDLC)
• Systems investigation – understanding the
problem
• Systems analysis – understanding the
solution
• Systems design – creating the logical and
physical components

14. Systems Development Life Cycle
(SDLC)
• Systems implementation – placing
completed system into operation
• Systems maintenance and review –
evaluating the implemented system

15. Entity-Relationship Model
(E-R Model)
• Used to depict the relationship that exists
among entities

16. E-R Model Symbols

17. Relationships
• The following relationships can be
included in an E-R Model:
– One-to-one
– One-to-many
– Many-to-many

18. One-to-one Relationship
• Each occurrence of data in one entity is
represented by only one occurrence of data
in the other entity
• Example: Each individual has just one
Social Security Number (SSN) and each
SSN is assigned to just one person

19. One-to-many Relationship
• Each occurrence of data in one entity can be
represented by many occurrences of the
data in the other entity
• Example: A class has only one instructor,
but each instructor can teach many classes

20. Many-to-many Relationship
• Data can have multiple occurrences in both
entities
• Example: A student can take many classes
and each class is composed of many
students

21. Example E-R Model

22. Normalization
• Determines required tables and columns for
each table
• Multi-step process allows designer to take
the raw data to be collected about an entity
• Used to reduce or control data redundancy

23. Attributes of Books
• isbn : a value string used to identify any book.
• Title: Book’s title
• Publication Date: A value of DATE type.
• Cost: Publisher’ price
• Retail: Sale’s price.
• Category: Computer, Fiction Science, etc.
• Publisher: Publisher’ house.
• Contact: Sale representative.

24. Representation of Books

25. Unnormalized Data
Contains repeating groups in the Author
column in the BOOKS table

26. First-Normal Form (1NF)
• Primary key is identified. A Primary key is
a field that serves to uniquely identify each
record.
• Repeating groups are eliminated (each entry
a separated record).

27. First-Normal Form (1NF)
ISBN and Author columns together create a
composite primary key

28. Composite Primary Key
• More than one column is required to
uniquely identify a row
• When a primary key consists of more or
one field, another problem may occurs---
partial dependency - a column/ns is/are
only dependent on a portion of the primary
key
The fields describing the book depend of
the book itself not upon who wrote.

29. Second-Normal Form (2NF)
• Partial dependency must be eliminated
– Break the composite primary key into
two parts, each part representing a
separate table (for example, Author)

30. Second-Normal Form (2NF)
BOOKS table in 2NF

31. Third-Normal Form (3NF)
Publisher contact name has been removed

32. Summary of Normalization Steps
• 1NF: eliminate repeating groups, identify
primary key
• 2NF: table is in 1NF and partial
dependencies eliminated
• 3NF: table is in 2NF and transitive
dependencies eliminated

33. Linking Tables
• Once tables are normalized, make certain
tables are linked
• Tables are linked through a common field
• A common field is usually a primary key in
one table and a foreign key in the other
table

35. Graphical Representation for Books
Column Name ISBN Title Publication
Date
Cost Retail Category PublId
Key Type PK FK1
Null/
Unique
NN,U NN
FK Ref
Table
Publisher
FK Ref Columns PublId
Data type CHAR CHAR DATE NUMBER NUMBER CHAR NUMBER
Maximum
Length
10 35 11 11 25 5
Sample Data 8843172113 DATABASE 11/AGO/2003 69.75 89.75 computers 1234

36. Lab # 1
• Find the graphical representations of tables
considered in the Pet Shop.

37. Specialization
• Top-down design process; we designate subgroupings
within an entity set that are distinctive from other
entities in the set.
• These subgroupings become lower-level entity sets
that have attributes or participate in relationships that
do not apply to the higher-level entity set.
• Depicted by a triangle component labeled ISA (E.g.
customer “is a” person).
• Attribute inheritance – a lower-level entity set
inherits all the attributes and relationship participation
of the higher-level entity set to which it is linked.

38. Generalization
• A bottom-up design process – combine a
number of entity sets that share the same
features into a higher-level entity set.
• Specialization and generalization are simple
inversions of each other; they are represented
in an E-R diagram in the same way.
• The terms specialization and generalization are
used interchangeably.

39. UML
• UML: Unified Modeling Language
• UML has many components to graphically
model different aspects of an entire software
system
• UML Class Diagrams correspond to E-R
Diagram, but several differences.

40. Structured Query Language
(SQL)
• Data sublanguage
• Used to:
– Create or modify tables
– Add data to tables
– Edit data in tables
– Retrieve data from tables