CHAPTER 7: STORING ORGANIZATIONAL INFORMATION - DATABASES

- Information is stored in databases

DATABASE- maintains information about various types of objects(inventory), events (transactions),
people (employees) and places (warehouses)

Database models include:

•  Hierachical database model - information is organized into a free-like structure (using parent/child relationships) in such a way that it cannot have too many relationships.
• Network database model - a flexible of representing objects and their relationships.
• Relational database model - stores information in the form logically related ti-dimensional tables.
  
  

HIERARCHICAL STRUCTURE

NETWORK STRUCTURE

RELATIONAL STRUCTURE

ENTITIES AND ATTRIBUTES

• Entity - A person, place, thing, transaction, or event about which information is stored.
• Attributes - Characteristics or properties of an entity class.

Keys and Relationships

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

• Primary key - a field (or group of fields) that uniquely in=dentifies a gien 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.

- Database advantages from a business perspective include:

• Increased flexibility
• Increased scalability and performance
• Reduced information redudancy
• Increased information intergrity (quality)
• Increased information security

1. Increased Flexibility

•  A well-designed database should: Handle changes quickly and easily, provide users with different views, have only one physical views, have multiple logical views
• Example : a mail-order bussiness, people view different format (logical views) but same physical view.
• Physical views: deals with the physical storage of onformation on a storage device, example hard disk.
• Logical views: focuses on how users logically access information.

2. Increased Scalability and Performance

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

3. Reduced Information Redundancy

• Database reduce information redundancy
• Redundancy - the duplication of information of storing the same information in multiple places
• Inconsistency is one of the primary problems with redundant, information-difficult to decide which is the most current and most accurate.

4. Increase Information Intergrity (Quality)

• Information integrity- measures the quality of information
• Integrity constraint- rules that help ensure the quality of information
• Realtional integrity constraint- rule that enforces basic and fundamental information-based constraints.
• Business-critical intergrity constraint- rule that enforce business rules vital to an organization's  succes and often require more insight and knowledge than relational integrity constraints.

5. Increased Information Security

• Information is an organization asset and must be protected
• Databases offer several security features including:

1.  Password - provides authentication of the user
2. Access level - determines who has access to the different types of information
3. Access control - determines types of user access, such as rea-only access.

6. Database Management Systems

•  Databases managemnt systems (DBMS) - software  through which users and application programs interact with database.
• Data-driven Websites- an interactive website kept constantly updated relevant to the needs of its custoers through the use of a database

Data-Driven Website Business Advantages

- Development

- Content managemtn

- Future expandability

- Minimizing human error

- Cutting production and update costs

- More efficient

- Improved Stability

7. Integrating Information among Multiple Databases

• Integration- allows separate systems to communicate directly with each other
• Forward intergration - takes information entered into a given systems and send it automatically to all downstream systems and processes
• Backward Intergration - take information entered into a given system and send it automatically to all upstream systems and processes. 

FORWARD INTERGRATION

BACKWARD INTEGRATION

• Without integration, an organization will spend considerable time entering the same info multiple system and suffer from the low quality and inconsistency typically embedded in redundant info