RELATIONAL DATABASE FUNDAMENTALS
Information is everywhere in an organization
Information is stored in databases
· Database – maintains information about various types of objects (inventory), events (transactions), people (employees), and places (warehouses)
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 many 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
Entities and Attributes
Entity – a person, place, thing, transaction, or event about which information is stored
Attributes (fields, columns) – characteristics or properties of an entity class
Keys and Relationships
Primary key – a field (or group of fields) that uniquely identifies a given entity in a table
Foreign key – a primary key 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 redundancy
· Increased information integrity (quality)
· Increased information security
Increased Flexibility
A well-designed 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
• Have multiple logical views
Logical view – focuses on how users logically access information
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 to increased demands
• Performance – measures how quickly a system performs a certain process or transaction
Reduced Information Redundancy
• One of the primary goals of a database is to eliminate information redundancy by recording each piece of information in only one place
• Databases reduce information redundancy
Redundancy – the duplication of information or storing the same information in multiple places
• Inconsistency is one of the primary problems with redundant information
Increase Information Integrity (Quality)
• Information integrity – measures the quality of information
• Integrity constraint – rules that help ensure the quality of information
Increased Information Security
• Information is an organizational asset and must be protected
• Databases offer several security features including:
Password – provides authentication of the user
Access level – determines who has access to the different types of information
Access control – determines types of user access, such as read-only access
DATABASE MANAGEMENT SYSTEMS
software through which users and application programs interact with a database
DATA-DRIVEN WEB SITES
A data-driven Web site is an interactive Web site kept constantly updated and relevant to the needs of its customers through the use of a database. Data-driven Web sites are especially useful when the site offers a great deal of information, products, or services. Web site visitors are frequently angered if they are buried under an avalanche of information when searching a Web site. A data-driven Web site invites visitors to select and view what they are interested in by inserting a query, which the Web site then analyzes and custom builds a Web page in real-time that satisfies the query. The figure displays a Wikipedia user querying business intelligence and the database sending back the appropriate Web page that satisfies the user’s request.
Data-Driven Web Site Business 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 enables the site to grow faster than would be possible with a static site. Changing the layout, displays, and functionality of the site (adding more features and sections) is easier with a data-driven solution.
• Minimizing human error: Even the most competent programmer charged with the task of maintaining many pages will overlook things and make mistakes. This will lead to bugs and inconsistencies that can be time consuming and expensive to track down and fix. Unfortunately, users who come across these bugs will likely become irritated and may leave the site. A well-designed, data-driven Web site will have ”error trapping” mechanisms to ensure that required information is filled out correctly and that content is entered and displayed in its correct format.
• Cutting production and update costs: A data-driven Web site can be updated and ”published” by any competent data entry or administrative person. In addition to being convenient and more affordable, changes and updates will take a fraction of the time that they would with a static site. While training a competent programmer can take months or even years, training a data entry person can be done in 30 to 60 minutes.
• More efficient: By their very nature, computers are excellent at keeping volumes of information intact. With a data-driven solution, the system keeps track of the templates, so users do not have to. Global changes to layout, navigation, or site structure would need to be programmed only once, in one place, and the site itself will take care of propagating those changes to the appropriate pages and areas. A data-driven infrastructure will improve the reliability and stability of a Web site, while greatly reducing the chance of ”breaking” some part of the site when adding new areas.
• Improved Stability: Any programmer who has to update a Web site from ”static” templates must be very organized to keep track of all the source files. If a programmer leaves unexpectedly, it could involve re-creating existing work if those source files cannot be found. Plus, if there were any changes to the templates, the new programmer must be careful to use only the latest version. With a data-driven Web site, there is peace of mind, knowing the content is never lost—even if your programmer is.
Integrating Information among Multiple Databases
• 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
• One of the biggest benefits of integration is that organizations only have to enter information into the systems once and it is automatically sent to all of the other systems throughout the organization
• This feature alone creates huge advantages for organizations because it reduces information redundancy and ensures accuracy and completeness
• Without integrations an organization would have to enter information into every single system that requires the information from marketing and sales to billing and customer service
Integrating Information among Multiple Databases
Building a central repository specifically for integrated information
• The above figure displays an example of customer information integrated using this method
• Users can create, read, update, and delete in the main customer repository, and it is automatically sent to all of the other databases
• This method does not follow the business process when building the integrations
• Business-critical integrity constraints still need to be built to ensure information is only ever entered into the customer repository, otherwise the information will become out-of-sync
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