Sunday, 1 September 2013


What is databases ?
Maintain info about various types of objects (inventory), event (transaction),
people (employees) and places (warehouses).
For example UiTM student portal and facebook 

Relational Database Fundamental

Database models include :
  • Hierarchical database model - information is organized into a tree-like structure (using parent/child relationships) in such a way that it cannot have too relationships. 
  • Network database model - a flexible way of representing objects and their relationships
  • Relational database model - stores information in the form of logically related two-dimensional tables

Entity and Attribute

  • Entity - A person , place, thing, transaction, or event about which information is stored.
  • Attributes (field, columns) - characteristics or properties of an entity class.
Keys and Relationships

Primary keys and foreign keys identify the various entity classes (tables) in the database
  • Primary key - a field (or group of fields) that uniquely identifys a given entity in a table.
  • Foreign key - a primary of one table that appears an attribute in another table and acts to provide a logical relationship among the two tables.
Relational Database Advantages

Database advantages from a business perspective include :
  • Increased flexibility
  • Increased scalability and performance
  • Reduced information integrity (quality)
  • Increased information redundancy
  • Increased information security
Increased flexibility

A well-designed database should:
  • Handle changes quickly and easily
  • Provide users with different views
  • Have only physical view - deals with the physical storage of information on a storage device
  • Have multiple logical view

    Increased Scalability and Performance

    A database must scale to meet increased demand, while maintaining acceptable performance levels.
    • Scalability : refers to how well a system can adapt tp increased demands
    • Performance : measures how quickly a system performs a certain process or transaction 

    Reduced Information Redundancy

    • Databases reduce information redundancy - The duplication of information or storing the same information in the multiple places.
    • Inconsistency is one of the primary problems with redundant information.
    Increased Information Integrity (Quality)

    • Information integrity : measures the quality of information
    • Integrity constraint : rules that help ensure the quality of information

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