Organizing Data and Information

What is Data?? Numbers, characters, images, or other method of recording,

in a form which can be assessed by a human or (especially)input into a computer, stored and processed there, ortransmitted on some digital channel.

Data on its own has no meaning, only when interpreted by somekind of data processing system does it take on meaning andbecome information.

People or computers can find patterns in data to perceiveinformation, and information can be used to enhanceknowledge. Since knowledge is prerequisite to wisdom, wealways want more data and information.

What is Data??

Database Concepts

Data is a valuable resource collection of facts/figures/observations storing, organizing, retrieving, sorting,

maintaining data are important activities.

to organize data you must understand:

Some Key Terminology

FIELDS: A field is a single attribute of an entity Entity can be person, place, object, event,

idea Field Names: Each field is given a name

Examples: Name, Age, Salary Field Value:

Specific value/content of a field name Ex.: “Joe Blow”, 30, 23000

Some Key Terminology

RECORDS:Group of related field values belonging to a

given entity under consideration FILE:

Group of related records DATABASE:

Group of related files

Section 035Fields: Field Names: Field Value:

TCU ID Preferred Last Full Name Grd Basis Status Units106-501-303 Josie Benor Benor,Josie Leiser GRD Enrolled 3106-407-964 Chris Bosillo Bosillo,Christopher Wayne GRD Enrolled 3106-430-298 Michael Buono Buono,Michael Vincent GRD Enrolled 3106-379-381 Christopher Byars Byars,Christopher R. GRD Enrolled 3106-373-583 Katie Clement Clement,Katie R. GRD Enrolled 3106-387-806 Cole Davis Davis,Cole St.Clair GRD Enrolled 3106-353-873 James Day Day,James Curtis GRD Enrolled 3106-360-584 Emery Dodson Dodson,Emery Anne GRD Enrolled 3106-414-752 Hilary Felton Felton,Hilary Schrader GRD Dropped 3

Records

Data Hierarchy

CharacterCharacter

FieldField

RecordRecord

FileFile

DatabaseDatabase

Bits (0 or 1)Bits (0 or 1)

Data Hierarchy

Data Management Concerned with

Data accuracy reliable source of data reliable data entry timeliness.

Security protecting data to keep it from being misused

or lost (authorized access, backup) Data maintenance

procedures used to keep data current (adding, changing, deleting)

The Traditional Approach To Data Management

Limitations of Files

Data Redundancy – duplicate fields in multiple files

Data Inconsistency – identical fields have different data

Data Isolation – inaccessibility of data from other applications

Security – nonexistent

Data Integrity – accuracy of data in records

Database

A Database - an organized collection of related data that can service many applications at the same time.

A collection of data is not per se a database. Organized means that you can easily find

what you want. Related means that the data have

significance when viewed together.

Data Entities and Attributes

Entity Generalized class of people, places, or things

for which data is collected, stored, and maintained

Examples of entities include employees, customers, and inventory

Attributes A characteristic of an entity

For example, employee number, last name, first name, hire date, and department number are attributes for an employee

Keys

Key: A field or set of fields in a record that

is used to identify the record Primary Key

A field or set of fields that uniquely identifies the record

Keys and Attributes

The Database Approach to Data Management

Advantages of 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

Framework for program development

Better overall protection of the data

Shared data and information resources

Disadvantages of Database Approach

Relatively high cost of purchasing and operating a DBMS in a mainframe operating environment

Increased cost of specialized staff Increased vulnerability

Database Models

Hierarchical (tree) Network Relational

Hierarchical Database Model

Network Database Model

Relational Database Model

A Relational Database Model

Link via a common field between

tables

Relational database and keys

A relational database is a collection of tables that are related to one another based on a common field.

A field, or a collection of fields, is designated as the primary key. The primary key uniquely identifies a record

in the table. When the primary key of one table is

represented in a second table to form a relationship, it is called a foreign key.

Relating tables using a common field

The primary key in the Employer table (EmployerID) is the common field that relates this table to the Position table.

PositionID is the primary key in the Position table. The EmployerID field is a foreign key in this table.

Primary keys can only have one occurrence in a table. Foreign keys may have multiple occurrences.

Linking Database Tables to Answer an Inquiry