CHAPTER 7: STORING ORGANIZATIONAL INFORMATION - DATABASES

Relational Database Fundamentals

• Information is everywhere in an organization.

• Information is stored in databases: 

        - Databases: Maintains information about various types of objects (inventory), events           (transactions), people (employees), and places (warehouse).

• Database models include: 

(a) 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 relationship.

(b) Network database model - A flexible way of representing objects and their many relationships.

(c) 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 Relationship

Primary keys and foreign keys identify the various entity classes (tables) in the database.

(a) Primary key - A field (or group of fields) that uniquely identifies a given entity in a table.

(b) 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:

(a) 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 a multiple logical views

• Logical view: Focuses on how users logically access information.

(b) 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 to quickly a system performs a certain process or                                        transaction.


(c) 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.

(d) Increase Information Integrity (Quality)

• Information  Integrity - Measures the quality of information.
• Integrity Constant - Rules that help ensure the quality of information.

       - Relational integrity constraint: Rule that enforces basic and fundamental

                                                       information-based constraints.

       - 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.

• Difference between relational integrity constraints and business-critical integrity constraints.

RELATIONAL INTEGRITY CONSTRAINTS	BUSINESS-CRITICAL INTEGRITY CONSTRAINTS
Users cannot create an order for a non-existent customer.	Product returns are not accepted for fresh product 15 days after purchase.
An order cannot be shipped without an address.	A discount maximum of 20 percent.

(e) 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 Websites

An interactive website kept constantly updated and relevant to the needs of its customers through the use of a database.

Data-Driven Website Business Advantages

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.

• Building a central repository specifically for integrated information.