Organizing Data and Information

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Organizing Data and Information

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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.

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What is Data??
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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

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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

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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

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Section 035
Fields Field Names Field Value
Records
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Data Hierarchy
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Data Hierarchy
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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)

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The Traditional Approach To Data Management
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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

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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.

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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

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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

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Keys and Attributes
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The Database Approach to Data Management
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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

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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

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Database Models

• Hierarchical (tree)
• Network
• Relational

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Hierarchical Database Model
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Network Database Model
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Relational Database Model
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A Relational Database Model
Link via a common field between tables
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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.

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Relating tables using a common field
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Linking Database Tables to Answer an Inquiry