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, or transmitted on some digital channel.charactersimagescomputerprocesseddigital channel Data on its own has no meaning, only when interpreted by some kind of data processing system does it take on meaning and become information.data processing systeminformation People or computers can find patterns in data to perceive information, and information can be used to enhance knowledge. Since knowledge is prerequisite to wisdom, we always want more data and information. knowledge

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 035 Fields: Field Names: Field Value: Records

Data Hierarchy Character Field Record File Database 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