InformationSystems

Software

Hardware Telecommunications

Data People

Chapter 4: Database Management

Databases Before the Use of Computers

• Data kept in books, ledgers, card files, folders, and file cabinets

• Long response time

• Labor-intensive

• Often incomplete or inaccurate

Key Database Issuesand Activities

• Entering and Querying Data

• Creating Database Reports

• Maintaining Data

Entering and Querying Data

• Use a form for data entry

• Use queries to retrieve information– Structured Query Language (SQL)– Query by example (QBE)

Creating Database Reports

• Report– A compilation of data organized and

produced in printed format

• DBMS packages include a report writer

• Graphics can be added

• Can be automatically updated by linking to data

To Efficiently Maintain Data

• Model the data

• Select a physical structure– Hierarchical– Network– Relational

• Normalization process– Incl. Update / insert / delete procedures

Data Modeling

• Ensures all needed data represented in the correct form,

• Identifies all the relationships that exists among data: “Associations”,

• Communicates assumptions about the data and relationships with the users of data.

Associations• Relationships among the entities in the

data structures

• Three types– One-to-one– One-to-many– Many-to-many

- U.S. Airways -

• The fifth largest airline in America, U.S. Airways--with 2500 jet flights per day--is using an IBM database system to better manage its in-flight meal and video services. By analyzing upgrade, no-show, and cancellation patterns, U.S. Airways can more accurately predict how many meals are needed on each flight. … (page 2-92)

Selecting a physical structure in which to store the data

• Hierarchical

• Network

• Relational

The Hierarchical Model

The Network Model

The Relational Model

Normalization

• A technique used to make complex databases more efficient

• Break one large table into several smaller tables– Eliminates all repeating groups in records– Eliminates redundant data

Redundant Data

Normalized Data

Logical vs. physical representation of data

• The same “number” can be:– An invoice number in sales– A billing number in accounting– A picking number in warehouse– A delivery ticket number in distribution

Recent Developments

• Databases and Client-Server Computing– Server holds the actual database– Clients hold software to work with the

database

Client/Server Database

Recent Developments

• Object-Oriented Databases (OODBs) – Treat tables, queries, etc., as reusable

objects

Recent Developments

• Data Mining (On-Line Analytical Processing)– Drill down from summary data to detailed data– Data Warehouses/Data Marts

• Integrates many large databases into one repository

• Table 4.3  Sample industry uses of data warehousing (adapted from: Boar, 1998).

Recent Developments

• Linking Web Site Applications to Organizational Databases– Users have Web view to organizational database– Improves customer contact and service– Adds security as a concern

- CNN Interactive -

• An example of successfully linking a large corporate database with a Web interface can be found at CNN Interactive. CNN Interactive provides a free, online custom news service to hundreds of thousands of subscribers around the world. … (page 2-109)

Effective Management of Databases

• Database Administrator (DBA)– Responsible for the development and

management of an organization’s databases

• Works with systems analysts on design

• Works with users and managers on managerial and organizational issues

• Responsible for implementing security features

Key Terms

• Databases: Collections of related data organized in a way that facilitates data searches.

• Database management systems: Software applications with which you can create, store, organize, and retrieve data for one or many databases.

• Entity: Things about which we collect data, such as people, courses, customers, or products.

• Tables: Collections of related records

about an entity type, where each row is a record and each column is a field.

• Field: Individual pieces of information about an entity, such as a person’s last name or social security number, stored in a database cell.

• Record: A collection of related fields about an entity, usually displayed as a row in a database.

 

• Form: A collection of blank entry boxes, each representing a field, which is used to enter information into a database.

•  • Querying: Requesting information from a

database.•  • Structured Query Language (SQL): The

most common set of commands used to request information from a database.

•  • Query by example (QBE): A capability of a

DBMS to enable us to request data by simply providing a sample or a description of the types of data we would like to see.

• Report: A compilation of data that is

organized and produced in a printed format.

•  • Data model: A representation of entities

and their relationships in the real world.•  • Primary key: A field included in a

database that can be used to uniquely identify each instance of an entity.

•  • Data type: Format for the data stored

within a field.

• Data dictionary: A repository that

describes data types, uses, storage requirements, rules that affect data, and so on.

•  • Hierarchical database model: A DBMS

approach in which entities are described in a parent-child relationship.

• Network database model: A DBMS approach in which entities can have multiple parent-child relationships.

• Relational database model: A DBMS

approach in which entities are presented as two-dimensional tables that can be joined together with common columns

•  • Normalization: A process of making

data structures simple and clear•  • Client/server architecture: A

distributed processing system in which a client application that needs data or software gets it from a server that is a source for some or all of the needed data or software.

• Database server: a powerful computer

that contains the database and responds to queries from client computers in a client/server application.

•  • Object-oriented databases: Database

management systems that follow the object-oriented approach of reusable objects, encapsulation, inheritance, and so on.

• Data mining: Sorting and analyzing information stored in organizational databases

 

• Data warehouses: Repositories integrating multiple large databases and other informational sources in a single repository or access point that is suitable for direct querying, analysis, or processing.

 • Data marts: Small-scale data warehouses

that contain a sub-set of the data for a single aspect of a company’s business (for example, finance, inventory, or personnel).

 • Database administrator: Person

responsible for the development and management of the organization’s databases.