Database – maintains information about various type of objects (inventory), events (transactions), people (employee) and places (warehouses)
Database models include :
Hierarchical database model – information is organized into a tree like structure which using parent/child relationships in such a way that it cannot have too many relationships.
Network database model – a flexible way of representing objects and their relationship
Relationship database model – store information In the form of logically related two-dimensional tables.
Entity – a person , place , thing, transaction or event about which information is stored
Attribute (fields, columns) - characteristics or properties of an entity class
Primary keys- field or group of field that uniquely identifies a given entity in a table
Foreign keys – a primary key of one table that appears an attribute in another table and acts to provide a logical relationship among the two table
The primary keys and foreign key identify the various entity classes (table) in the database.
The advantages of database :
Increase flexibility
A well design database should :
• Handle changes quickly and easily
• Provide users with different views
• Have only one physical view
Physical view – deals with the physical storage of information on a storage device. Example : hard disk
Increased scalability
A database must scale to meet increased demand , while maintaining acceptable performance levels
• Scalability – refers to how well a system can adapt to increased demand.
• Performance – measures how quickly a system performs a certain process or transaction.
Reduced information redundancy
Database reduce information redundancy
• Redundancy- the duplication of information or storing the same information in multiple places.
• Inconsistency is one of the primary problem with redundant.
Increased information integrity (Quality)
• Information integrity – measure the quality of information
• Integrity constraint – rules that help ensure the quality of information
Relation integrity constraint – rule that enforces basic and fundamental information based constraint.
Business critical integrity constraint – rule that enforce business vital to an organization’s knowledge than relational integrity constraints.
Increased information security
• Password – provides authentication of the user
• Access level – determines who has access to the different type of information
• Access control – determines type of user access such as read only access.
Database management system (DBMS) – software through which users and application programs interact with a database.
Data-driven web sites – an interactive web site kept constantly update and relevant to the needs of its customers through the use of a database.
Data-driven web site advantages :
• Development – allows the web site owner to make changes any time all without having to rely on a developer or knowing HTML programming. A well-structured, data driven web site enables updating with little or no training.
• Content management – a static web site requires a programmer to make updates. This adds an unnecessary layer between the business and its web content , which can lead to misunderstandings and slow turnarounds for desired changes.
• Future expandability – having a data-driven web site enable the site to grow faster thnk would be possible with a static site. Changing the layout , display, and functionality of the site is easier with data-driven solution.
Integration – allows separate systems to communicate directly with each other.
• Forward integration – takes information entered into a given system and sends it automatically to all downstream systems and processes.
• Backward integration – takes information entered into a given system and sends it automatically to all upstream systems and processes.
Without integration an organization will :
• Spend considerable time entering the same info in multiple system
• Suffer from the low quality and inconsistency typically embedded in redundant info
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