chapter 4 database processing. agenda purpose of database terminology components of database system...

Chapter 4

Database Processing

Agenda

• Purpose of Database• Terminology• Components of Database System• Multi-user Processing• Database Design• Entity-relationship Model• Database Administration• Database Security• Discussion, Design, and Case Study

Purpose of Database

• to keep track of things that involve more than one theme

Terminology - I

• Database– A collection of self-describing and integrated records

• The hierarchy of data elements– Bytes – columns – fields – rows (records) – tables (files or

relations) – database

• Database– A collection of tables plus relationships (in terms of) among rows

(records) in these tables

• Relationships– Primary key: a column or group of columns to identify a unique

row in a table– Foreign key: a non-key column or field in one table that links to a

primary key in another table

Hierarchy of Data Elements

Examples of Relationships Among Rows

Terminology - II

• Relational database– Tables– Relationship using primary key and foreign

key

• Metadata– The structure of the database– The data describe the data

• Field name, data type, description, property

Metadata Example (in Access)

Components of a Database

Components of Database System

• Database management system (DBMS): software– To create tables, relationships, and other structure– To process (read, insert, modify, or delete) data– To produce forms, reports, and queries through database

application– To administer (security, back up, recover, clean up, and

enhance performance) a database

• Structured Query Language (SQL)– An international standard language for processing a database

• Product types– Enterprise DBMS: IBM (DB2), Microsoft (SQL Server), Oracle

Corporation (Oracle), Open-source (MySQL)– Personnel DBMS: Microsoft (Access) for 15 or less users

Components of a Database Application System

Use of Multiple Database Applications

Four Application Programs on Web Server Computer

Multi-user Processing

• More than one user accessing a particular database table at same time

• Lost-update problem

• Lock

Database Design

• Create data model– Logical representation of database based on users view on the

business environment (user’s requirements)– Data and relationships that users want to track

• Create database design– The process of converting a data model into tables,

relationships, and data constraints– Normalization: the process of converting poorly structured tables

into two or more well-structured tables to avoid data integrity problems

• Users’ reveiw• Create database

Entity Relationship Model - I

• Components– Entity: physical object (rectangular)– Attributes: characteristics of the entity– Primary key: identifier– Relationship: primary key and foreign key (line)

• Normalization– The process of converting poorly structured tables into two or

more well-structured tables– Every table describe a single topic or theme– To avoid data integrity problems– To avoid generating incorrect and inconsistent information– Trade off between performance– Normal form

Entity Relationship Model - II

• Entity-relationship diagram– Entity: rectangular– Relationship: line

• One-to-one: 1:1• One-to-many (crow’s foot): 1:N• Many-to-many: N:M• Many-to-many relationship has to be changed to

two 1:N relationship via an intersection table• Maximum cardinality• Minimum cardinality

Database Development Process

Example Relationships Showing Minimum Cardinalities

Transforming a Data Model into a Database Design

Representing a 1:N Relationship - I

Representing a 1:N Relationship - II

Representing a N:M Relationship

Database Administration - I

• Functions– Manage the development, operation, and

maintenance of a database to achieve the organization’s objectives

– Balance conflicting goals to protect the database and maximize its availability for authorized use

• DBA– Database administrator or office of database

administration– an auditor, a consultant, sometimes a policeman, and

a diplomat working as a liaison between the users and professional developers

Database Administration - II

• DBA responsibilities– Database development– Database operation– Backup and recovery– Adopt new database change requirements– Create a steering committee consisting of key users

• Steering committee– Community-wide decisions regarding the

development, use, and maintenance of the database– Community-wide policies for the processing of the

database– Processing rights (minimum)

Database Security

• Firewall

• OS and DBMS patches

• Physical access security

• User accounts, roles, and minimum permission

• Processing and error logs

• Security emergency plan

Discussion

• Ethics (81a-b)– What should the company do to avoid the situation at first place?– What should the company do to properly handle Kelly’s case– What should Kelly do to avoid the stated consequence after

querying the database?– What could Kelly do to save his career?

• Opposing forces (97a-b)– What should the DBA of car dealer do to convince every

salesperson to build and use a solid sales information database?• Reflections (101a-b)

– What should the DBA of any organization to handle the changing requirements for a new database?

– What should the DBA of any organization to handle the new requirements for a existing database?

Relational Database Design

• Given the following entities and their attributes– Buyer (BuyerID, BuyerName)– Owner (OwnerID, OwnerName)– Property (PropertyID, PropertyAddres, OwnerID)– Agent (AgentID, AgentName)– Sales (SalesID, BuyerID, OwnerID, PropertyID,

AgentID, Price, Date)

• Design a relational database– Create primary key for every entity and the necessary

foreign key– Create an entity-relationship diagram

Case Study

• Assignment 22 (105)

• Case 4-1 (107-110): questions 1, 4, and 7 (add aircraft for 7)

• Case 4-2 (110-113): questions 1 and 2

Points to Remember

• Purpose of Database• Terminology• Components of Database System• Multi-user Processing• Database Design• Entity-relationship Model• Database Administration• Database Security• Discussion, Design, and Case Study