Data at the Core of the Enterprise

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Data at the Coreof the Enterprise
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Objectives

• Define of database systems
• Introduce data modeling and SQL
• Discuss emerging requirements of database systems

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DATA
?
INFORMATION
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Attributes of data

• Sharable
• Moveable
• Secure
• Accurate
• Timely
• Relevant

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Data hierarchy

• Bits
• Characters
• Fields (columns)
• Records (rows)
• Files (table)
• Database

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Why build a database?

• Handle large amounts of data
• Satisfy multiple users
• Make information retrieval faster
• Make data input faster
• Provide greater accuracy

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Database versus Database Management System (DBMS)

• Database is a self-describing collection of
  integrated files
• A DBMS is a complex computer program that acts as
  a data librarian, supervising the transfer of
  data between the end user and the database

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Advantages of DBMS

• More info from the same data
• Reduction of data duplication
• Improved data integrity
• Programs are independent of the data format
• Sharing of data resources

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and disadvantages

• Added expense
• More hardware may be needed
• If it crashes.
• Sophisticated design and programming required
• Additional training
• Security is critical

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Relational model

• Relation? Attribute? Tuple?
• Keys
• Primary and foreign
• Referential integrity
• Relational algebra

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Relational DB rules

• Every row must have exactly the same number of
  columns (fields or attributes)
• Each row can have only one value stored in each
  column (fields or attributes)
• A column must contain the same kind of value in
  every row of that column
• No two rows can be exactly the same
• The order of the rows or of the columns cant be
  used to provide information

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Terminology
Data Processing
Informal Relational DB
Formal Relational DB
  File
  Table
  Relation
Record
Row
Tuple
   
Field
Column
Attribute
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Data modeling

• Purpose control and visualization
• Process gathering requirements
• Results forms and diagrams

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Normalization

• Purpose
• Avoid anomalies
• Reduce redundancy
• Process
• Successive application of rules
• Bottom-up (data drives process)
• Move from first through fifth normal form
• Does it make more or less tables?

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Entity relationship modeling

• List the entities or objects in the environment
• People, things, transactions
• Describe the relationship between them
• A single row in table A can be related to how
  many rows in table B (one or many)
• A single row in table B can be related to how
  many rows in table A (one or many)

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ERD questions

• What are the subjects/objects of the business?
• data entities
• What unique characteristic(s) distinguishes each
  object from others of same type?
• primary key
• What characteristics describe each object?
• attributes
• How do you use this data?
• controls meaning

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ERD questions

• Over what period of time are you interested in
  this data? cardinality
  time dimensions
• Are all instances of each object the same?
• supertypes, subtypes, aggregations
• What events occur that imply associations between
  objects? relationships (cardinality
  degree)
• Is each activity or event always handled the same
  way or are there special circumstances?
• integrity rules, cardinality, time

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SQL

• Definition (DDL)
• CREATE, ALTER, DROP
• Manipulation (DML)
• SELECT, INSERT, UPDATE, DELETE
• Whats the most used sql command?

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General format of SELECT
SELECT DISTINCT item(s) FROM table(s)
WHERE condition GROUP BY columns
HAVING condition ORDER BY row(s)
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Emerging data requirements
Complex
Graphics
Video
Audio
HTML/ SGML
Video Streams
Spatial Data
Time Series
Unstructured
Structured
Images
Text
Current RDBMS
Audio Streams
Simple
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Summary

• Defined of database systems
• Introduced data modeling and SQL
• Discussed emerging requirements of database
  systems