Introduction to modern day database system

• Atomicity ensures that a transaction is either completely processed or not processed at all.
• Difference between data and information:

  • Data are raw facts
  • Information is the result of processing raw data to reveal meaning
  • Information requires context to reveal meaning
  • Raw data must be formatted for storage, processing, and presentation
  • Data are the foundation of information, which is the bedrock of knowledge
• Data management:

  • Focuses on proper generation, storage, and retrieval of data
• Drawbacks of File System:

  • Data redundancy: duplication of data leads to higher storage costs and poor access time
  • Data inconsistency: occurs when more than one record is stored but fails to update all
  • Data isolation: writing new application programs to retrieve data is difficult due to scattered data in various files
  • Dependency on application programs: changing files leads to changes in application programs
  • Atomicity issues: "All or nothing" principle in transactions
  • Data security: securing data from unauthorized access is challenging in file processing systems
• Structural and Data Dependence:

  • Structural dependence: access to a file is dependent on its own structure
  • Structural independence: change file structure without affecting data access
  • Data dependence: data access changes when data storage characteristics change
  • Data independence: data storage characteristics do not affect data access
• Database:

  • Shared, integrated computer structure that stores end-user data and metadata
  • Database management system (DBMS): collection of programs that manages structure and controls access to data
• Database Systems:

  • Consist of logically related data stored in a single logical data repository
  • DBMS eliminates most of file system’s problems
  • Stores data structures, relationships between structures, and access paths
• Role and Advantages of the DBMS:

  • Collection of programs that enables users to create and maintain databases and control all access to them
  • Intermediary between the user and the database
  • Enables data sharing, integrates users’ views of the data, improves data security, data integration, data access, decision making, and end-user productivity
• • Data integrity management: promotes and enforces integrity rules, minimizes redundancy, maximizes consistency
• DBMS Functions:

  • Data Dictionary Management: stores definitions of data elements and their relationships in a data dictionary
  • Data storage management: creates and manages complex structures required for data storage
  • Data transformation and presentation: transforms data to conform to required data structures
  • Security management: enforces user security and data privacy
  • Multiuser access control: ensures concurrent access does not affect integrity
  • Backup and recovery management: provides backup and data recovery for data safety and integrity
• Types of Databases:

  • Classified according to number of users, database location(s), and expected type and extent of use
  • Single-user database supports only one user at a time
  • Multiuser database supports multiple users at the same time
  • Centralized database: data located at a single site
  • Distributed database: data distributed across several different sites
  • Operational database: supports day-to-day operations
  • Data warehouse: stores data used for tactical or strategic decisions
• Database Design:

  • Focuses on design of database structure used for end-user data
  • Well-designed database facilitates data management and generates valuable information
  • Poorly designed database leads to bad decision making and organizational failure
• Database System Environment:

  • Consists of hardware, software, people, procedures, and data
  • Database systems are created and managed at different levels of complexity
  • Database technology already in use affects selection of a database system
• Summary:

  • Data are raw facts, information is the result of processing data
  • Accurate, relevant, and timely information is key to good decision making
  • Data are usually stored in a database
  • DBMS implements a database and manages its contents
• Hardware: all the system’s physical devices
• Software required for a database system:

  • Operating system software
  • DBMS software
  • Application programs and utility software
• People involved in a database system:

  • System and database administrators
  • Database designers
  • Systems analysts and programmers
  • End users
• Procedures that govern the design and use of the database system
• Data: the collection of facts stored in the database
• Database systems are created and managed at different levels of complexity
• Database solutions must be cost-effective and tactically and strategically effective
• Database technology already in use affects the selection of a database system
• Advantages of a DBMS:

  • Improved data sharing
  • Improved data security
  • Better data integration
  • Minimized data inconsistency
  • Improved data access
  • Improved decision making
  • Increased end-user productivity
• Types of databases can be classified according to:

  • Number of users
  • Database location(s)
  • Expected type and extent of use
  • Single-user database supports only one user at a time
  • Multiuser database supports multiple users at the same time
• Unstructured data exist in their original state

  Structured data result from formatting

  Semistructured data have been processed to some extent

  Extensible Markup Language (XML) represents data elements in textual format

  XML database supports semistructured XML data
• Importance of Database Design:

  • Focuses on the design of the database structure used for end-user data
  • Well-designed database facilitates data management and generates accurate and valuable information
  • Poorly designed database causes difficult-to-trace errors
• DBMS Functions:

  • Data Dictionary Management
  • Data storage management
  • Performance tuning
  • Data transformation and presentation
  • Security management
  • Multiuser access control
  • Backup and recovery management
  • Data integrity management
  • Database access languages and application programming interfaces
  • Database communication interfaces
• Lack of Design and Data-Modeling Skills:

  • Most users lack the skill to properly design databases
  • Data-modeling skills are vital in the data design process
• Database Systems and Other Organizational Information Management Systems:

  • Transaction processing systems
  • Management information systems
  • Decision support systems
• DBMS Applications:

  • Telecom Industry
  • Banking System
  • Sales
  • Airlines
  • Education
  • Online Shopping
• Summary:

  • Metadata is data about data
  • Database design defines the database structure
  • Well-designed database facilitates data management and generates valuable information
  • Poorly designed database leads to bad decision making and organizational failure
  • Databases evolved from manual and computerized file systems
• In a file system, data stored in independent files

  Each requires its own management program

  Some limitations of file system data management:

  • Requires extensive programming
  • System administration is complex and difficult
  • Changing existing structures is difficult
  • Security features are likely inadequate
  • Independent files tend to contain redundant data
  • Structural and data dependency problems
• Database management systems were developed to address file system’s inherent weaknesses

  DBMS present the database to the end user as a single repository

  Promotes data sharing

  Eliminates islands of information

  DBMS enforces data integrity, eliminates redundancy, and promotes security