C H A P T E R

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C H A P T E R
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• Organized Data and Information

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Data

• Data
• A necessity for almost any enterprise to carry
  out its business. Consists of raw facts, and when
  organized may be transformed into information.
• Database
• A collection of data organized to meet users
  needs

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Data Management

• In order to manage data it must be organized.
• It is organized in a hierarchy.

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The Hierarchy of Data
Checking Account Files Savings Account Files Loan
Account Files
Database
27439, Smith, Joe, 453.21, 1-3-98 34278, Watt,
Carol, 212.54, 2-6-99 43872, Yos, Tom, 3224.87,
3-8-97
Files (TABLES)
Records
27439, Smith, Joe, 453.21, 1-3-98
Fields
Smith (Last Name)
(S 01010011 in ASCII)
Characters
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The Hierarchy of Data
Database A collection of integrated and related
files.
File A collection of related records.
Record A collection of related fields.
Field A group of characters.
Character Basic building block of information,
represented by a byte.
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How Characters are Stored
Codes for Storing Data Character ASCII A 01
000001 B 01000010 ... Z 01011010 0 0
0110000 1 00110001 ... 9 00111001
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How Characters are Stored

• Codes for Storing Data
• ASCII
• American Standard Code for Information
  Interchange.
• The most popular code.
• Used by most computer manufactures.
• 7 bit code. (Eight bit never standardized.)
• 128 characters.

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The Traditional Approach to Data Management

• The Traditional Approach
• Separate files are created and stored for each
  application program.
• Very common from the 50s through the 80s.

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The Traditional (File Oriented) ApproachBanking
Example
Smalltown National Bank 1965
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The Traditional (File Oriented) ApproachBanking
Example
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The Traditional (File Oriented) Approach

• PROBLEMS
• (1) DATA REDUNDANCY
• Same data stored on different files.
• Name is on checking, savings, and loan files.
• Address is on checking, savings, and loan files.
• Telephone number is on checking, savings, and
  loan files.

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The Traditional (File Oriented) Approach

• PROBLEMS
• DATA REDUNDANCY CAUSES
• Unnecessary data entry.
• Duplicated data on one file may not get changed
  on another file
• during an update or deletion.
• Leads to a lack in DATA INTEGRITY.

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The Traditional (File Oriented) Approach

• PROBLEMS
• (2) DATA INTEGRITY
• Data redundancy leads to a lack of data
  integrity.
• Lack of data integrity errors in database

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The Traditional (File Oriented) Approach

• PROBLEMS
• (3) LACK OF DATA INTEGRATION
• With separate file systems, it is difficult to
  produce reports which require data from
  separate file systems.
• EXAMPLE The bank manager might want a report
  showing the names of customers who use all the
  bank's services checking, savings and loans.

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The Traditional (File Oriented) Approach

• PROBLEMS
• (4) PROGRAM-DATA DEPENDENCE
• If the size of a field in a record changes, all
  the programs which access that record must be
  modified.
• EXAMPLE When ZIP codes changed from 5 digits to
  9 digits, all programs which accessed ZIP codes
  had to be modified.

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The Traditional (File Oriented) Approach
SUMMARY (1) CAUSES DATA REDUNDANCY. (2) LACKS
DATA INTEGRITY. (3) LACKS DATA INTEGRATION. (4)
CAUSES PROGRAM-DATA DEPENDENCY.
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The Database Approach

• The Database Management System Approach
• A pool of related data is shared by multiple
  application programs. Rather than having separate
  data files, each application uses a collection of
  data that is either joined or related in the
  database.

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Advantages to the Database Approach

• Improved strategic use of corporate data
• Reduced data redundancy
• Improved data integrity
• Easier modification and updating
• Data and program independence
• Better access to data and information
• Standardization of data access
• A framework for program development
• Better overall protection of the data
• Shared data and information resources

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Disadvantages to the Database Approach

• Relatively high cost of purchasing and operating
  a DBMS in a mainframe operating
  environment.
• This applies to mainframes, and some
  minicomputers only.
• Increased cost of specialized staff.
• Increased vulnerability.

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Database Terms

• ENTITIES
• A generalized class of people, places, things, or
  events (objects) about which data are collected,
  stored, and maintained.

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Database Terms

• ATTRIBUTES
• An Attribute is a characteristic of an Entity.
• A field or set of fields in a record that is
  used to identify
• the record.

Attributes
ATTRIBUTES OF CHECKING Acct Last
First Balance Start Date 27439 Smith Joe
453.21 1-3-98 34278 Watt Carol 212.54
2-6-99 43872 Yos Tom 224.87 3-8-97
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Database Terms

• PRIMARY KEY
• A field or set of fields that UNIQUELY
  identifies the record.
• Account Number is the only UNIQUE field in this
  record.

Primary Key
ATTRIBUTES OF CHECKING Acct Last
First Balance Start Date 27439 Smith Joe
453.21 1-3-98 34278 Watt Carol 212.54
2-6-99 43872 Yos Tom 224.87 3-8-97
.
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Database Terms

• KEY
• A field or set of fields that is used to
  identify a record or records.

Keys
ATTRIBUTES OF CHECKING Acct Last
First Balance Start Date 27439 Smith Joe
453.21 1-3-98 34278 Watt Carol 212.54
2-6-99 43872 Yos Tom 224.87 3-8-97
.
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Database Terms

• SECONDARY KEY
• A Key which is NOT a primary key.

How much money do I have in my checking
account? I cant remember my checking account
number, but my last name is Yos.
ATTRIBUTES OF CHECKING Acct Last
First Balance Start Date 27439 Smith Joe
453.21 1-3-98 34278 Watt Carol 212.54
2-6-99 43872 Yos Tom 224.87 3-8-97
.
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Database Terms

• DATA ITEM
• A specific value of an attribute.

Data Item (Examples)
ATTRIBUTES OF CHECKING Acct Last
First Balance Start Date 27439 Smith Joe
453.21 1-3-98 34278 Watt Carol 212.54
2-6-99 43872 Yos Tom 224.87 3-8-97
.
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Database Terms

• DATA MODELING
• This is map or diagram of entities and their
  relationships.
• These maps or diagrams show the how the database
  is organized.
• A popular diagramming technique is called
  entity-relationship diagram.

Entity-relationship diagram
.
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Database Terms
Entity-relationship diagram
Name
Dept
Student
Professor
Takes Class
Major
Name
1
N
Classes
ID
Relation- ship
Entity
Attribute
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Database Terms

• Distributed Database
• A database in which the actual data may be
  spread across several smaller databases connected
  via telecommunications devices.

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Database Terms

• Data Warehouse
• A relational database management system.
• Designed SPECIFICALLY to support management
  decision making.
• Does NOT meet the needs of a TPS.
• Contains current and historical data.

Looks as if we should relocate our manufacturing
facility.
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Database Terms

• Data Mining
• AUTOMATED discovery of patterns and
  relationships in a data warehouse.
• Uses advanced statistical techniques and machine
  learning.
• Used to predict as well as discover.

Look. I think we are experiencing a large
increase in credit card fraud.
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Data Modeling and Database Models

• Data Model
• A map or diagram of entities and their
  relationships.
• Enterprise data modeling
• Data modeling done at the level of the entire
  organization.
• Entity-Relationship (ER) diagrams
• A data model that uses basic graphical symbols to
  show the organization of and relationships
  between data.

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Entity Relationship (ER) Diagram for a Customer
Ordering Database
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A Relational Data Model

• Relational Data Model
• All data elements are placed in two-dimensional
  tables, called relations, that are the logical
  equivalent of files.

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Relational Database Terms

• Selecting
• Data manipulation that eliminates rows
• (records) according to certain criteria.
• Projecting
• Data manipulation that eliminates columns in a
  table.
• Joining
• Data manipulation that combines two or more
  tables.
• Linked
• Related tables in a relational database together.