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Database application

Database application. Data vs. Information. Data: Raw fact Information: Data processed to reveal meaning Data is unprocessed information. File-based system. Disadvantages Require extensive programming (3GL) Time consuming Data Redundancy Different and conflicting versions of same data

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Database application

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  1. Database application

  2. Data vs. Information • Data: • Raw fact • Information: • Data processed to reveal meaning • Data is unprocessed information

  3. File-based system • Disadvantages • Require extensive programming (3GL) • Time consuming • Data Redundancy • Different and conflicting versions of same data • Lack of data integrity • Deletion and insertion anomalies are common • No security (Hard to mimplement)

  4. File-based system (con’t) • Disadvantages • No security (Hard to implement) • Data Dependence • Change in file’s data characteristics requires modification of data access programs • Structural Dependence • Change in file structure requires modification of related programs

  5. File-based system (con’t) • Disadvantages • E.g.

  6. Definition • Database: is an entity in which data can be stored in a structured manner, with as little redundancy as possible. Different programs and different users must be able to use this data • A database is a self-describing collection of related records or tables • Contains: • User Data • Metadata: data about the structure of a database

  7. Why Database • Reduce redundancy • Sharing of data • Restricting unauthorized access to data • Multiple interfaces to different classes of users • Enforcing integrity constraints on the database • Providing backup and recovery services • Enforcing standards • Reduced application development time

  8. Database System Types • Number of users • Single-user vs. Multiuser Database • Location • Centralized vs. Distributed • Use • Production or transactional • Decision support or data warehouse

  9. Database Management System • DBMS: software system that manages execution of users applications to access and modify database data so that the data security, data integrity, and data reliability is guaranteed for each application and each application is written with an assumption that it is the only application active in the database.

  10. Database Management System

  11. Database system environment • Hardware (System’s Physical devices) • Computer, Peripherals, Network • Software • Operating system: manages hardware components • Windows, Unix, Linux etc • DBMS: manages database • MS Access, SQL Server, Oracle, DB2, Mysql • Application and utility software: support access and manipulate data • Generate information for decision making • Help to manage database system

  12. Database system environment (con’t) • People • System administrator • Hardware system support • Database administrator: • Manage DBMS • Database designer • Programmers • End users: • Data • Procedures

  13. Database system environment

  14. DBMS Functions • Data dictionary management • Definition of the data elements and their relationships are • Remove data and structure dependencies. • Data storage management • Structures required for data storage • Data transformation and presentation • Translate logical request into command to physically locate and retrieve the request data

  15. DBMS Functions (con’t) • Security management • Enforce user security & data privacy within DB • Multiuser access control • Use sophisticate algorithm • Ensure concurrency • Data integrity management • Enforce integrity rules

  16. DBMS Functions (con’t) • Database access language and application programming interfaces • Eg. SQL • Database communication interfaces • Accept end user requests via multiple, different environment • Backup and recovery management

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