Chapter 5

Introduction to

Database Management

Data

• Vital organizational resource

• Data resource management is a managerial action that applies technology to the task of managing data

Data Concepts

• Character - a character is a single element of data and can be alphabetic, numeric, or some other ‘legal’ character

• Field - A field is a grouping of characters that describes an attribute of and entity

• Record - A logical grouping of fields relating to the same entity

Data Concepts cont.

• Records can be fixed length or variable length

• File - A group of related records is a file or commonly known as a table. Tables are classified by levels of permanence– transaction - daily sales or production– master - employee_master, item_master– history - usually backups

Database

• A database is an organized and integrated collection of records

• Data in a database is independent of the programs that use the data

The Database Management Approach

• Foundation of modern data management• Database management approach - data records

and objects are consolidated and accessed by multiple application programs

• Database Management System - software interface between users and databases - uses DBMS software to create, interrogate, update, and maintain a database to provide information for users

Database Management Approach

• Three common activities– update and maintain common databases to

reflect transactions and organizational data– provide information for end users applications– provide easy interface for ad hoc (on demand)

requests, generation of reports, and database interrogation

DBMS

• A database management system is a set of programs that control four necessary functions in the database world– database development– database interrogation– database maintenance– application development

Database Development

• Database management application packages allow for the development of databases

• Database administrators (DBAs) use a data definition language to design and develop tables, relationships, and a data dictionary

• Data dictionary - A catalog or directory of information about the data (meta data)

Database Interrogation

• Database interrogation (extracting data/information) is accomplished by using a query or a report generator

• Query language offer– immediate response to request– no difficult programming

Database Interrogation cont

• A report generator offers– immediate video or paper response to queries– No difficult programming– Can format or design reports to meet individual

needs/preferences

SQL and QBE

• Structured Query Language - A ‘standardized’ language that allows for simple database interrogation

• Basic form for SQL statement is – Select …..– From……– Where…..

SQL and QBE

• Query By Example - query language similar to SQL except the query is written in the ‘background’ as the user points and clicks

• Graphical and Natural queries are essentially point and click utilities that are translated into SQL

Database Maintenance

• Database maintenance occurs through transaction processing and the ACID functions – A - add– C - change– I - inquiry– D - delete

Application Development

• Databases are the backbone of system development

• A data manipulation language allows for necessary data handling needs

Database types

• There are several major types of databases – operational databases– data warehouses– distributed – external

Operational Databases

• These databases store data that is necessary for the operations of an organization such as transaction databases, subject area databases

• Very important for this type of database to be accurate

Data Warehouse

• A data warehouse stores data from previous years or time periods that are not necessary for the current operations of an organization

• May be subdivided into DATA MARTS that contain certain data elements– Data mining is the process of extracting data,

trend analysis, and historical patterns

Distributed Databases

• Can be copies of organizational databases that reside in different geographical areas, on different servers (for functional areas), or on handheld or labtop devices

External Databases

• Privately owned online databases usually accessible for a fee

• Can be free

• Usually associated with Internet

Data Resource Management

• Data resource management involves several tasks– Database Administration– Data Planning– Data Administration

Database Administration

• Provides for the development and maintenance of the data dictionary

• Monitoring of database and resource performance

• Enforcement of standards and security

Data Planning

• Corporate planning and analysis function

• Data architecture for firms data needs (must fit within the strategic missions)

• Should be a major issue in strategic planning

• Long range planning

Data Administration

• Establishment and enforcement of policies and procedures for managing data resource

• Collect, store, and disseminate information in an organizationally standardized manner

• Planning and support of data and the establishment of data planning activities

• Develop policies and standards for database design

Benefits/Limitations

• Reduction of replication and redundant data

• Data integration

• Users can obtain information in more usable form

• Programming is simplified

• Data integrity and security is ensured

Benefits/Limitations

• Complexity

• Can be very expensive to develop and maintain

• Large investment LARGE

• More difficult processing procedures (must work through and additional layer of software)

Technical Foundationsof Database Management

• Data resources must be organized in a logical manner

• This allows for easy access, efficient processing, quick retrieval of data

• Multiple structures………...

Hierarchical

• Early mainframe packages used the hierarchical structure of database management– Treelike structure– Records are dependent on a root record– Relationships are one to many (only related to

the element above it)

Network Structure

• Able to represent more complicated structures and relationships

• Still used in many mainframe packages

• Allows for many to many relationships

• Access is not one dimensional and can follow many paths

Relational Structure

• Most popular in use today

• Used by most micro databases, also used in mini systems and mainframe systems

• Data elements stored in tables

• Table related through the use of a common field

MultidimensionalDatabase Structure

• Variation of the relational model

• Compact and easy to use

• Support OLAP

Object OrientedStructure

• The key technology of multimedia web-based applications

• An object consists of data plus the instructions to be applied

• Inheritance is the acceptance of characteristics of other objects

Database Access

• Databases rely on identifying characteristics called key fields or in the case of older DB types a pointer field

• Key field is the primary identifier

• Must be unique among all other records

Sequential Access

• Records are stored in a specific order based on the key field

• Sequential processing is fairly fast when dealing with similar records (fixed length)

• Requires sorting, indexing, etc.

• Best in batch processing situations

Direct Access

• No fixed arrangement of records

• Works with immediate response systems

• Three ways for direct access to occur– Key transformation– Index– Indexed Sequential access

Next Week

• Chapter 5 data base planning and design

• Chapter 6 IS for Business Operations and E-commerce