Transcript Chapter 4

Chapter 4
Database Processing
Agenda
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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
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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
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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
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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
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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
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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
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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