Chapter 7 . Storing Organizational Information - Database

Relational Database Fundamentals

• Information is stored in database

- Database - maintains information about various types of objects (inventory), events (transactions), people (employees), and place (warehouse).

• Database models :

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

• the rows in each table contain the entities

Attributes (fields, columns) - characteristics or properties of an entity class

• the columns in each table contain the attributes 

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 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

1. 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 of information on a storage device
  - have multiple logical views
  Logical view - focuses on how users logically access information
  - e.g : a mail-order buss-2 people view diff format (logical views) but same physical view

2. 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

3. Reduced information redundancy

• 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 - difficult to decide which is most current and most accurate

4. Increased information integrity (quality)

• Information integrity - measures the quality of information
• Integrity constraint - rules that help ensure the quality of information
  -Relational integrity constraint - rule that enforces basic and fundamental information - based constraints
  - e.g : users cannot create an order for a nonexistent customer : an order cannot be shipped without an address
  Business-critical integrity constraint - rule that enforce business rules vital to an organization's success and often require more insight and knowledge than relational integrity constraints
  - e.g : Product returns are not accepted for fresh product 15 days after purchased : A discount maximum of 20 percent

5.Increased information security

• Information is an organizational asset and must be protected
• Databases offer several security features :
  - 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 (DBMS)

• software through which users and application programs interact with a database

Data-Driven Web Sites

• an interactive Web site kept constantly updated and relevant to the needs of its customers through the use of a database

Data-driven Web site business advantages :

• Development - allows the web sites owner to make changes any time - all without having a rely on a developer or knowing HTML programming.
• Content management - a static web site requires a programmer to make updates. This adds is an unnecessary layer between the business and its web content, which can lead to misunderstanding 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 functionally of the site (adding more features and sections) is easier with a data-driven solution.
• Minimizing human error - 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 that they would with a static site.
• More efficient - With a data-driven solution, the system keeps track of the templates, so users do not have to.
• Improved stability - with a data-driven website, there is peace of mind, knowing the content is never lost - even if your programmer is.

Data-Driven Business Intelligence

Integrating Information among Multiple Databases

• Integration - allows separate systems to communicate directly with each other
  - Forward integration - takes information entered into a given systems 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 into in multiple system
  - suffer from the low quality and inconsistency typically embedded in redundant info.