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Database Management
An Introduction
Goals For Today:
Describe why databases have become so important to modern organizations
Describe what database and database management systems are and how they work.
Explain four emerging database trends:– (1) client / server computing, – (2) object-oriented databases, – (3) data mining, and – (4) integrating Web applications
Database Defined
Database: – A collection of related data organized in a way
that facilitates data searches. What are some examples of Databases?
Example of a Student Database
Types of Data Collected in a Typical Student Database
Databases Before the Use of Computers
Data was stored in:– books– ledgers– card files– folders– file cabinets– or simply in people’s heads!?
Computers make the process of storing and managing data easier
The Database Approach
Database Management System– software application which allows you to
create, store, organize, and retrieve data from a single database or many databases.
– Example: MS Access Entity
– something you collect data about– Examples: people or classes
A Database Contains the Following: Tables
– how entities are represented in a database, where each row is a record and each column a field.
Fields– individual pieces of information
Record– collection of related fields within one entity
Sample Data Table (page 2-94 in your book)
Key Database Issues and Activities Entering and Querying Data Creating Database Reports Data Structure Data Type
Entering Data
Data Entry:– process of getting information into a database– possible methods of data entry:
Data Entry Professional, Electronic Files, Historical Records, or Web Based (Forms)
Querying Data Querying:
– how we get information from a database Structured Query Language (SQL):
– most common language used to interface with databases
– Example:SELECT DISTINCTROW STUDENT_ID, GRADE
FROM GRADES
WHERE GRADE = “A”
ORDER BY STUDENT_ID;
Querying Data continued Query By Example (QBE)
– enables you to fill out a grid, or template, in order to construct a description of the data you would like to retrieve.
Creating Database Reports Report:
– A compilation of data from the database that is organized and produced in a printed format.
– Typically produced on paper, but also can be displayed on-screen.
– Example: Quarterly Sales Report
Data Structure
Database has two parts:– Data– Data Structure: how the data is organized.
Data Model:– representation of entities and their relationships to the
real world Primary Key:
– a unique identifier in the database– one or more fields
Data Structure continued
Primary Key is Student ID
Data Type
Data Type:– each field in the database needs to be of a
certain type– Examples: text, number, dates
Data Dictionary:– a document (often published online) prepared
by the database designers to aid users in data entry.
Data Dictionary Example:
Students Table
Primary Key Field Name Field Type Field Length
yes Student ID Number 9
no Last Name Text 20
no First Name Text 15
Database Management Systems Approaches The Hierarchical Model The Network Model Relational Model Normalization Associations
The Hierarchical Model Records in parent entities can have many
child records, but each child can have only one parent.
Parent
Child
The Network Model
In this case you can have multiple children and parents Parents
Children
The Relational Model– A good relational database design eliminates
unnecessary data duplications and is, therefore, easier to maintain
– Relationship: joining two tables on a common field
Relationship
Normalization
A technique used to make complex databases more efficient and easier to handle
Eliminates Redundant Data
Normalization continuedDatabase w/redundant data
Database after Normalization
Three Types of Associations or Relationships
– One-to-One Each team has only one home stadium, and each home stadium has
only one team– Team ID Team Name Location Stadium ID
– One-to-Many Each Player is on only one team, but each team has many players
– Player ID Player Name Position Team ID
– Many-to-Many Each player participates in many games, and each game has many
players
Team 1 Team 2 Date Player ID Points Minutes Fouls
Recent Developments AffectingDatabase Design and Use Databases and Client / Server Computing Object-Oriented Databases Data Mining Linking Web Site Applications to
Organizational Databases
Databases and Client / Server Computing
Database application is divided into two parts: – Database Server
where all data is stored on a powerful machine
– PC Client the program used to manipulate the data resides on an
individual user’s computer
Object-Oriented Databases
treat tables, queries, and other components as generic reusable OBJECTS (rather than data) that can be mixed and matched and used in many applications (e.g. MS Excel and MS Access).
Most of today’s database applications have some of these Object characteristics.
Data Mining
Allows companies to sort and analyze information to better understand customers, products, markets, or any other phase of their business for which data has been captured.
Example: Grocery Store Club Cards
Data Mining continued Data Warehouses
– An integration of multiple, large databases and other information sources into a single repository or access point that is suitable for direct querying, analysis, or processing
Data Warehouse Examples
TELECOMMUNICATIONS REPRESENTATIVE COMPANIES
Analysis of the following: AT&T
Call volumes Ameritech
Equipment sales Belgacom
Customer profitability British Telecom
Costs Telestra AustraliaTelecom Ireland
Inventory Telecom Italia
Purchasing leverage with suppliers
Frequent buyer program management
Data Mining continued Data Marts
– A small-scale data warehouse that contains a subset of the data for a single aspect of a company’s business
– Examples: finance, inventory, or personnel
Linking Web Site Applications to Organizational Databases Example:
– many comapies are enabling users of their Web Site to:
view product catalogs, check inventory, and place orders
these are all actions that read and write to the organizations’ databases.
Goals For Today:
Described why databases have become so important to modern organizations
Described what database and database management systems are and how they work.
Explained four emerging database trends:– (1) client / server computing, – (2) object-oriented databases, – (3) data mining, and – (4) integrating Web applications