Database Systems Background Review Dr. Muhammad Shafique

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Database Systems Background ReviewDr. Muhammad
Shafique
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Outline

• Databases and Database Users
• Database System Concepts and Architecture

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Databases and Database Users (1)

• Database concepts
• Database
• A database represents some aspect of the real
  world
• A database is a logically coherent collection of
  data with some inherent meaning.
• A database is designed, built, and populated with
  data for a specific purpose.
• It has an intended group of users and some
  preconceived applications in which these users
  are interested.
• Database Management System
• A database management system (DBMS) is a
  collection of programs that enables users to
  create and maintain a database.

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Databases and Database Users (2)

• Typical DBMS Functionality
• Define a database
• Construct or Load the Database
• Manipulating the database
• Concurrent Processing and Sharing
• Other features
• Protection or Security measures to prevent
  unauthorized access
• Active processing to take internal actions on
  data
• Presentation and Visualization of data

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Databases and Database Users (3)
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Databases and Database Users (4)

• Characteristics of the Database Approach
• Self-describing nature of a database system
• Insulation between programs and data
• Data Abstraction
• program-data independence
• Support of multiple views of the data
• Sharing of data and multi-user transaction
  processing

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Databases and Database Users (5)

• Database Users
• Database administrators
• Database Designers
• End-users
• Casual
• Naïve or Parametric
• Sophisticated
• Stand-alone

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Databases and Database Users (6)

• Advantages of Using the Database Approach
• Controlling redundancy
• Sharing of data among multiple users
• Restricting unauthorized access to data
• Providing persistent storage
• Providing Storage Structures for efficient Query
  Processing
• Providing backup and recovery services
• Providing multiple interfaces to different
  classes of users
• Representing complex relationships among data
• Enforcing integrity constraints on the database
• Drawing Inferences and Actions using rules

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Databases and Database Users (7)

• Additional Implications of Using the Database
  Approach
• Potential for enforcing standards
• Reduced application development time
• Flexibility to change data structures
• Availability of up-to-date information
• Economies of scale

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Databases and Database Users (8)

• Historical Development of Database Technology
• Early Database Applications
• Hierarchical and Network Models
• Relational Model based Systems
• Object-oriented applications
• Data on the Web and E-commerce Applications

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Databases and Database Users (9)

• Extending Database Capabilities
• Scientific Applications
• Image Storage and Management
• Audio and Video data management
• Data Mining
• Spatial data management
• Time Series and Historical Data Management
• The above gives rise to new research and
  development in incorporating new data types,
  complex data structures, new operations and
  storage and indexing schemes in database systems.
  

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Database System Concepts and Architecture (1)

• Data model
• A collection of concepts that can be used to
  describe the structure of a database
• Categories of data models
• Conceptual (high-level, semantic) data models
• Logical/Implementation (representational) data
  models
• Physical (low-level, internal) data models

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Database System Concepts and Architecture (2)

• Schemas and Instances
• Database Schema
• The description of a database is called the
  database schema, which is specified during
  database design and is expected not to change
  frequently
• Schema Diagram
• Schema Construct
• Database Instance
• The actual data stored in a database at a
  particular moment in time. Also called database
  state (or occurrence).

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Database System Concepts and Architecture (3)

• Database Schema Vs. Database State
• Database State
• Initial Database State
• Valid State
• Distinction
• The database schema changes very infrequently
• The database state changes every time the
  database is updated.
• Schema is also called intension, whereas state is
  called extension.

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Database System Concepts and Architecture (4)

• Three-Schema Architecture
• Internal schema
• Conceptual schema
• External schemas
• Mappings
• Transformations from one schema level to the
  other are needed to translate requests and data.
• Programs refer to an external schema, and are
  mapped by the DBMS to the internal schema for
  execution

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Database System Concepts and Architecture (5)
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Database System Concepts and Architecture (6)

• Data Independence
• Logical Data Independence
• Physical Data Independence
• DBMS Languages
• Data Definition Language (DDL)
• Storage Definition Language (SDL)
• View Definition Language (VDL)
• Data Manipulation Language (DML)
• DML commands (data sublanguage) can be embedded
  in a general-purpose programming language (host
  language)
• DML commands can be applied directly (query
  language).

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Database System Concepts and Architecture (7)

• DBMS Interfaces
• Stand-alone query language interfaces
• Programming interfaces
• Pre-compiler Approach
• Procedure (Subroutine) Call Approach
• User-friendly interfaces
• Menu-based
• Forms-based
• Graphics-based
• Natural language
• Speech as Input (?) and Output
• Web Browser
• Parametric interfaces
• Interfaces for the DBA

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Database System Concepts and Architecture (8)

• Database System Utilities
• Loading data
• Backing up
• Reorganizing
• Performance monitoring
• Sorting
• User monitoring
• Data compression

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DBMS Component Modules
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Database System Architectures (1)

• Centralized

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Database System Architectures (2)

• Client-Server (two-tier logical)

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Database System Architectures (3)

• Client-Server (two-tier physical)

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Database System Architectures (4)

• Client-Server (three-tier)
• Presentation layer
• Business logic layer
• Database services layer

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References

• Textbook Chapter 1
• Textbook Chapter 2

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Summary

• Databases and Database Users
• Database System Concepts and Architecture