CHAPTER 3CHAPTER 3DATA RESOURCE DATA RESOURCE

MANAGEMENTMANAGEMENT

Learning ObjectivesLearning Objectives

Examine the Examine the managerial and managerial and organizational organizational requirements for requirements for managing data as a managing data as a resource. resource.

Foundation conceptsFoundation concepts A computer system organizes data in a A computer system organizes data in a

hierarchyhierarchy that starts with that starts with bytes and progresses to bytes and progresses to fields,fields, records, records, files, andfiles, and databases. databases.

BIT

BYTE

FIELD

RECORD

FILE

DATABASE

FILE ORGANIZATIONFILE ORGANIZATION BIT: the smallest unit of data a computer can handle.BIT: the smallest unit of data a computer can handle. BYTE:BYTE: Combination of BITS called a byte, represents a Combination of BITS called a byte, represents a

CHARACTER which can be a letter, a number or CHARACTER which can be a letter, a number or another symbol.another symbol.

FIELD: A grouping of characters into a word, a group of FIELD: A grouping of characters into a word, a group of words, or a complete number (such as words, or a complete number (such as person’s nameperson’s name or or ageage).).

RECORD: A group of related fields, such as the RECORD: A group of related fields, such as the student’s namestudent’s name, , the course takenthe course taken, , the datethe date, and , and the the gradegrade comprise a RECORD. comprise a RECORD.

FILE: A collection of similar RECORDS. FILE: A collection of similar RECORDS. DATABASE: A group of related files makes up a DATABASE: A group of related files makes up a

DATABASE. DATABASE.

DATABASEDATABASE

ORGANIZATION’S ELECTRONIC ORGANIZATION’S ELECTRONIC LIBRARYLIBRARY

STORES & MANAGES DATASTORES & MANAGES DATA

IN A CONVENIENT FORMIN A CONVENIENT FORM

**

Bit

Byte

Field

Record

0, 1

01001010 (Letter J in ASCII)

John Stewart (NAME field)

John Stewart IS 101 F02 B+NAME COURSE DATE GRADE

FileJohn Stewart IS 101 F02 B+Karen Taylor IS 101 F02 AEmily Vincent IS 101 F02 C

NAME COURSE DATE GRADE

Database

Course fileFinancial

file

Personalhistory file

HIERARCHY

ExampleStudent Database

KEY FIELDKEY FIELD Every record on a file should contain at Every record on a file should contain at

least one field that uniquely identifies least one field that uniquely identifies instances of that record so that record can instances of that record so that record can be retrieved, updated and sorted. be retrieved, updated and sorted.

This identifier field is called KEY FIELD.This identifier field is called KEY FIELD. Social security number for a personnel Social security number for a personnel

record would be a key field. record would be a key field.

File organizationFile organization In the database, the individual database is a collection of In the database, the individual database is a collection of

related related attributesattributes about about entitiesentities. . A record describes an A record describes an ENTITYENTITY. An ENTITY is something . An ENTITY is something

you collect data about, such as people or classes. you collect data about, such as people or classes. A A recordrecord is a collection of related attributes about a is a collection of related attributes about a

single entity. single entity. Each record typically consists of many Each record typically consists of many attributesattributes which which

are individual pieces of information. are individual pieces of information. For example, order number, order date, order account, For example, order number, order date, order account,

item number, and item quantity would each be an item number, and item quantity would each be an attribute of the entity order. attribute of the entity order.

Order number

Order date

Item number

Quantity Amount

4340 02/08/03 1583 2 17.40

Key field

Entity=ORDERAttributes

fields

The simple data tableThe simple data table

ID NumberID Number Last NameLast Name First NameFirst Name MajorMajor

209345209345 BordenBorden ChrisChris SociologySociology

213009213009 ChanChan LisaLisa FinanceFinance

4578945789 AustinAustin JohnJohn LawLaw

Entity: Student Attribute types

Record (one row)

Attribute

Database Management Systems Database Management Systems (DBMS)(DBMS)

A DBMS is a software application with which you A DBMS is a software application with which you create, store, organize, and retrieve data from a create, store, organize, and retrieve data from a single database or several databases.single database or several databases.

In the traditional file environment each functional In the traditional file environment each functional area tended to develop systems in isolation from area tended to develop systems in isolation from other functional areas. other functional areas.

Accounting, finance, manufacturing, human Accounting, finance, manufacturing, human resources all developed their own systems and resources all developed their own systems and data files. data files.

The organization is saddled with hundreds of The organization is saddled with hundreds of programs with no one who knows what they do, programs with no one who knows what they do, what data they use, and who is using the data.what data they use, and who is using the data.

DBMS

DBMSDBMS

DBMS is a software that permits to centralize data, DBMS is a software that permits to centralize data, manage them effectively, and provide access to the manage them effectively, and provide access to the stored data by application programs. stored data by application programs.

Software to create & maintain dataSoftware to create & maintain data Enables business applications to extract data.Enables business applications to extract data. Rather than storing data in separate files for each Rather than storing data in separate files for each

application, data are stored physically to appear to users application, data are stored physically to appear to users as being stored in only one location.as being stored in only one location.

Microsoft Access is an example of a popular DBMS for Microsoft Access is an example of a popular DBMS for personal computers. personal computers.

DBMSDBMS

DBMS software enables end users to DBMS software enables end users to create and manage their own database create and manage their own database applications. applications.

Most DBMSs have a specialized language Most DBMSs have a specialized language called a called a data manipulation languagedata manipulation language that is that is used to manipulate data in the database.used to manipulate data in the database.

STRUCTURED QUERY LANGUAGE STRUCTURED QUERY LANGUAGE (SQL)(SQL)

SQL is a data manipulation language to SQL is a data manipulation language to access, read and update data from access, read and update data from databases.databases.

Most common language used to Most common language used to interface with the databases.interface with the databases.

**

SQLSQL

The most important SQL commands:The most important SQL commands: SELECTSELECT: lists the columns from tables that the : lists the columns from tables that the

user would like to see in a result table.user would like to see in a result table. FROMFROM: identifies the tables or views from which : identifies the tables or views from which

the columns will be selected. the columns will be selected. WHEREWHERE: includes conditions for selecting : includes conditions for selecting

specific rows (records) within a single table and specific rows (records) within a single table and conditions for joining multiple tables.conditions for joining multiple tables.

SQLSQL

Part numberPart

descriptionUnit price

137145150152

Door latchDoor handle

Door sealCompressor

22.5026.256.00

70.00

Suppliernumber

4058203810581125

Database

Suppliernumber

405820381125

CBM Inc.Ace Inc.

Bryant Corp.

Suppliername

Supplier address

44 Winslow, Gary, IN 44950Rte, 101, Essex, NJ 07763

51 Elm, Rochester, NY 11349

PART

SUPPLIER

SQLSQL

Suppose you wanted to see the Part_Number, Suppose you wanted to see the Part_Number, Part_Description, and Unit_Price for each part in the Part_Description, and Unit_Price for each part in the PART table. You would specify:PART table. You would specify:

SELECT Part_Number, Part_Description, Unit_PriceSELECT Part_Number, Part_Description, Unit_Price

FROM PART;FROM PART; The results of using the SELECT statement to select The results of using the SELECT statement to select

only the columns Part_Number, Part_Description and only the columns Part_Number, Part_Description and Unit_Price from all rows in the PART table.Unit_Price from all rows in the PART table.

Part numberPart

descriptionUnit price

137145150152

Door latchDoor handle

Door sealCompressor

22.5026.256.00

70.00

SQLSQL Suppose, you wanted to see the same data only for Suppose, you wanted to see the same data only for

parts in the PART table with unit prices less than $25.00. parts in the PART table with unit prices less than $25.00. You would specify:You would specify:

SELECT Part_Number, Part_Description, Unit_PriceSELECT Part_Number, Part_Description, Unit_Price

FROM PART;FROM PART;

WHERE Unit_Price<25.00WHERE Unit_Price<25.00

Part numberPart

descriptionUnit price

137150

Door latchDoor seal

22.506.00

The results of using a conditional selection to select only parts that meet the condition of having unit prices less than $25.

Data manipulation languageData manipulation language

Many DBMS packages have a simpler Many DBMS packages have a simpler way of interfacing with the databases-way of interfacing with the databases-using a concept called using a concept called query by examplequery by example (QBE).(QBE).

It enables us to fill out a grid, or template, It enables us to fill out a grid, or template, in order to construct a sample of the data in order to construct a sample of the data we want to see. we want to see.

Database TrendsDatabase Trends1.Data Warehouses1.Data Warehouses

Database that stores current and historical data Database that stores current and historical data of potential interest to managers throughout the of potential interest to managers throughout the company. company.

This data is extracted for various operational This data is extracted for various operational systems and external sources including web site systems and external sources including web site transactions.transactions.

The data from these diverse applications are The data from these diverse applications are copied into the data warehouse database as copied into the data warehouse database as often as needed (hourly, weekly, daily, monthly).often as needed (hourly, weekly, daily, monthly).

Data WarehousesData Warehouses

The data are standardized into a common data The data are standardized into a common data model and consolidated so that they can be model and consolidated so that they can be used across the enterprise for management used across the enterprise for management analysis and decision making. analysis and decision making.

The data are available for anyone to access as The data are available for anyone to access as needed but cannot be altered.needed but cannot be altered.

Much like a physical warehouse for products Much like a physical warehouse for products and components, the data warehouse stores and components, the data warehouse stores and distributes data on computer-based and distributes data on computer-based information systems. information systems.

Operationaldata

Historicaldata

Operational data

Historical data

External data

Externaldata

INTERNALDATASOURCES

EXTERNALDATASOURCES

Extract andtransform

DataWare-house

Informationdirectory

DataAccess and

analysis

•Data mining•Reports

Components of a data warehouse

2. Data marts2. Data marts Companies can build enterprise-wide data Companies can build enterprise-wide data

warehouses where a central data warehouses where a central data warehouse serves the entire organization, warehouse serves the entire organization, or they can create smaller, decentralized or they can create smaller, decentralized warehouses called warehouses called data martsdata marts. .

Small data warehouse for special function, Small data warehouse for special function, e.g., Focused marketing based e.g., Focused marketing based

on customer info.on customer info.

Data martsData marts Subset of a data warehouse in which a summarized or Subset of a data warehouse in which a summarized or

highly focused portion of the organization's data is highly focused portion of the organization's data is placed in a separate database for a specific population placed in a separate database for a specific population of users. of users.

Each data mart contains a subset of the data for a Each data mart contains a subset of the data for a single aspect of a company’s business, for ex. finance, single aspect of a company’s business, for ex. finance, inventory, or personnel. inventory, or personnel.

Data marts have been popular among small and medium Data marts have been popular among small and medium sized businesses and among departments within larger sized businesses and among departments within larger companies.companies.

Data marts typically contain tens of gigabytes of data, as Data marts typically contain tens of gigabytes of data, as opposed to the hundreds of gigabytes in data opposed to the hundreds of gigabytes in data warehouse. warehouse.

The cost of data mart is typically less than $1 million, The cost of data mart is typically less than $1 million, while the cost for a data warehouse can exceed $10 while the cost for a data warehouse can exceed $10 million. million.

DATABASE ADMINISTRATIONDATABASE ADMINISTRATION

DEFINES & ORGANIZES DATABASE DEFINES & ORGANIZES DATABASE STRUCTURE AND CONTENTSTRUCTURE AND CONTENT

DEVELOPS SECURITY PROCEDURESDEVELOPS SECURITY PROCEDURES DEVELOPS DATABASE DOCUMENTATIONDEVELOPS DATABASE DOCUMENTATION MAINTAINS DBMSMAINTAINS DBMS

**

Management requirements for Management requirements for database systemsdatabase systems

The database is an organizational The database is an organizational discipline, a method, rather than a tool or discipline, a method, rather than a tool or technology.technology.

It requires organizational change.It requires organizational change. Without management support and Without management support and

understanding, database efforts fail.understanding, database efforts fail. The critical elements in a database The critical elements in a database

environment are data administration, data environment are data administration, data planning, and database management.planning, and database management.

ELEMENTS OF DATABASE ELEMENTS OF DATABASE ENVIRONMENTENVIRONMENT

DATABASE MANAGEMENT

SYSTEM

DATA

ADMINISTRATION DATABASE

MANAGEMENT

USERS

DATA PLANNING

Data administrationData administration

The organizations must develop a data The organizations must develop a data administration function for managing administration function for managing (collecting, storing, and dissemination of (collecting, storing, and dissemination of all types of data) the organization's data all types of data) the organization's data resources.resources.

Data administration is responsible for the Data administration is responsible for the specific policies and procedures through specific policies and procedures through which data can be managed as an which data can be managed as an organizational resource.organizational resource.

Data planningData planning

The organization requires enterprise-wide The organization requires enterprise-wide planning for data.planning for data.

Enterprise analysis, which addresses the Enterprise analysis, which addresses the information requirements of the entire information requirements of the entire organization is needed to develop organization is needed to develop databases.databases.

The purpose of it is to identify the key The purpose of it is to identify the key entities, attributes, and relationships that entities, attributes, and relationships that constitute the organization's data.constitute the organization's data.

Database managementDatabase management

Databases require new software and a new staff Databases require new software and a new staff specially trained in DBMS’ techniques as well as specially trained in DBMS’ techniques as well as new data management structures.new data management structures.

Most corporations develop a database design Most corporations develop a database design and management group within the corporation and management group within the corporation that is responsible for defining and organizing that is responsible for defining and organizing the structure and content of the database and the structure and content of the database and maintaining the database. maintaining the database.

Advantages of DBMSAdvantages of DBMS

DBMS can manage hundreds of tables DBMS can manage hundreds of tables simultaneously.simultaneously.

Helps us to manage tremendous volume and Helps us to manage tremendous volume and complexity of interrelated data.complexity of interrelated data.

Prevents unnecessary redundancies of data.Prevents unnecessary redundancies of data. Improved data sharing.Improved data sharing. Improved data quality.Improved data quality. Improved data accessibility.Improved data accessibility.

Database StructuresDatabase Structures

In all information systems, data resources In all information systems, data resources must be organized and structured in some must be organized and structured in some logical manner.logical manner.

Contemporary DBMS uses different Contemporary DBMS uses different database models to keep track of entities, database models to keep track of entities, attributes and relationships.attributes and relationships.

Database StructuresDatabase Structures

Hierarchical Hierarchical NetworkNetwork Relational Relational Object-orientedObject-oriented

TYPES OF RELATIONSTYPES OF RELATIONS

ONE-TO-ONE: ONE-TO-ONE: STUDENT ID

ONE-TO-MANY:ONE-TO-MANY:CLASS

STUDENTA

STUDENTB

STUDENTC

MANY-TO-MANY:MANY-TO-MANY:

STUDENTA

STUDENTB

STUDENTC

CLASS1

CLASS2

HIERARCHICAL DATA MODELHIERARCHICAL DATA MODEL

Hierarchical DBMS depict data logically as one-Hierarchical DBMS depict data logically as one-to-many relationships.to-many relationships.

The hierarchical DBMS presents data to users in The hierarchical DBMS presents data to users in a treelike structure.a treelike structure.

To the user, each record looks like an To the user, each record looks like an organization chart with one top-level segment organization chart with one top-level segment called the root. called the root.

An upper segment is connected logically to a An upper segment is connected logically to a lower segment in a parent-child relationship. lower segment in a parent-child relationship.

Used for structured, routine types of transaction Used for structured, routine types of transaction processing.processing.

ROOT

FIRST CHILD

2nd CHILD

RatingsRatings SalarySalary

CompensationCompensation JobJobAssignmentsAssignments

PensionPension InsuranceInsurance HealthHealth

BenefitsBenefits

EmployerEmployer

HIERARCHICAL DATA MODELHIERARCHICAL DATA MODEL

NETWORK STRUCTURENETWORK STRUCTURE

Network DBMS depict data logically as many-to-Network DBMS depict data logically as many-to-many relationships.many relationships.

More flexible than the hierarchical structure in More flexible than the hierarchical structure in support of databases for many types of business support of databases for many types of business operations.operations.

A typical many-to-many relationship for a A typical many-to-many relationship for a network DBMS is the student-course network DBMS is the student-course relationship. There are many courses in the relationship. There are many courses in the university and many students. A student takes university and many students. A student takes many courses and a course has many students.many courses and a course has many students.

NETWORK DATA MODELNETWORK DATA MODEL

MANY-TO-MANY:MANY-TO-MANY:

STUDENTA

STUDENTB

STUDENTC

CLASS1

CLASS2

RELATIONAL DBMSRELATIONAL DBMS

The most popular type of DBMS today for PCs as well as The most popular type of DBMS today for PCs as well as for larger computers and mainframes is the relational for larger computers and mainframes is the relational DBMS.DBMS.

It can relate data stored in one table to data in another It can relate data stored in one table to data in another as long as the two tables share a common data element.as long as the two tables share a common data element.

Easier for programmers to work with and easier to Easier for programmers to work with and easier to maintain than the hierarchical and network models.maintain than the hierarchical and network models.

Leading mainframe relational database management Leading mainframe relational database management systems include IBM’s DB2 and Oracle from the Oracle systems include IBM’s DB2 and Oracle from the Oracle Corporation.Corporation.

MS Access is a PC relational database management MS Access is a PC relational database management system.system.

Part numberPart

descriptionUnit price

137145150152

Door latchDoor handle

Door sealCompressor

22.5026.256.00

70.00

Suppliernumber

4058203810581125

Suppliernumber

405820381125

CBM Inc.Ace Inc.Bryant

Suppliername

Supplier address

44 Winslow, Gary, IN 44950Rte, 101, Essex, NJ 07763

51 Elm, Rochester, NY 11349

PART SUPPLIER

RELATIONAL DBMS

Select Part_number=137 or 152 Join by Supplier_number

Part numberSuppliernumber

Suppliername

Supplier address

137152

40581125

CBM Inc.Bryant

44 Winslow, Gary, IN 4495051 Elm, Rochester, NY 11349

Combined data from two different tables and only selected attributes are displayed.

Object-oriented DBMSObject-oriented DBMS Many applications today and in the future will require Many applications today and in the future will require

databases that can store and retrieve not only databases that can store and retrieve not only structured numbers and characters but also drawings, structured numbers and characters but also drawings, images, photographs, voice, and full-motion video.images, photographs, voice, and full-motion video.

Stores data & procedures as objects.Stores data & procedures as objects. Conventional DBMSs are not well suited to handling Conventional DBMSs are not well suited to handling

graphics-based or multimedia applications. graphics-based or multimedia applications. They are becoming more popular because they can They are becoming more popular because they can

be used to manage the various multimedia be used to manage the various multimedia components or Java applets used in Web applications components or Java applets used in Web applications which typically integrate pieces of info from a variety which typically integrate pieces of info from a variety of sources.of sources.

CREATING A DATABASECREATING A DATABASE

To create a database, one must go through two To create a database, one must go through two design exercises:design exercises:

CONCEPTUAL DESIGNCONCEPTUAL DESIGN PHYSICAL DESIGNPHYSICAL DESIGN

**

CREATING A DATABASECREATING A DATABASECONCEPTUAL DESIGN:CONCEPTUAL DESIGN:

Abstract model from a business Abstract model from a business perspective.perspective.

It describes how data will be grouped.It describes how data will be grouped. It establishes end-user needs.It establishes end-user needs.

**

CREATING A DATABASECREATING A DATABASEPHYSICAL DESIGN:PHYSICAL DESIGN:

Detailed model by database specialists Detailed model by database specialists How data are to be physically stored How data are to be physically stored

and accessed on the storage devices and accessed on the storage devices

**

CREATING A DATABASECREATING A DATABASE

EEntity-relationship diagramntity-relationship diagram

Database designers document the logical Database designers document the logical data model with an data model with an entity-relationship entity-relationship diagram (ERD)diagram (ERD) which is a methodology for which is a methodology for documenting databases illustrating the documenting databases illustrating the relationship between various entities in the relationship between various entities in the database. database.

ENTITY- RELATIONSHIP DIAGRAMENTITY- RELATIONSHIP DIAGRAM

M

1

M

1

ORDER

CAN HAVE

PART

SUPPLIER

CAN HAVE

ORDER: #, DATE, PART #, QUANTITY

PART: #, DESCRIPTION, UNIT PRICE, SUPPLIER #

SUPPLIER: #, NAME, ADDRESS

Entities

Relationships

Entity Attributes