CHAPTER 7 Storing Organizational Information Database

1. Learning Outcomes

1.1  Define the fundamental concepts of the relational databases model

1.2  Evaluating the advantages

1.3  Compare relational integrity constraints and business-critical integrity constraints

1.4  Describe the benefits
1.5  Describe the two primary methods


2. Relational Database Fundamentals

2.1 Define the fundamental concept of the relational database model ?

>   A database maintain information about the various types of objects (inventory), events                        (transaction),   people (employees) and places (ware houses)
>   Databases models include :

• Hierarchical database model - information is organized into a tree-like structure that allows repeating information using parents or child relationship in such a way that it cannot have too many relationship. It will were widely used in the first mainframe databases managements systems. 
• Network database model - is a flexibility way of representing objects and their relationship. 
• Relational databases model - is a type of databases that store information in the form of logically related two dimensional tables. Two dimensional means that in one web or network we can know many things in many way not just focus in one section. 

For example, Facebook social network is not focus only in one function but in Facebook if we click in other function the pages will proceed to other function in the same time without need to open new tab.

                                                                                                                                      

                          


A cube is one way to illustrate relations among data as it helps to visualize data intersections. While it is easiest for us to picture a three-dimensional cube, a relational database stores data in many dimensions.

2.2 Entities and Attributes

>  Entity - a person, place, thing, transaction or event about which information is stored

• The row in each table contain the entities 

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

• The columns in each table contain the attributes

2.3  Keys and Relationship

>  Primary keys - a field 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 ables

3. Relational Database Advantages

3.1  Increased Flexibility

>  A well-designed database should

   - Handle changes quickly and easily

   - Provide users with different view

•  Physical view - deals with the physical storage of information

   - Have multiple logical views

• Logical view - focuses on how users logically access information

   - Exp: a mail-order buss-2 people view diff format but same physical view

3.2 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 - measure how quickly a system performs a certain process or transaction

3.3 Reduced Information Redundancy

>  Database reduce information redundancy

• Redundancy - the same 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

3.4 Increase Information Integrity (Quality) 

>  Information integrity - measure 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
• Exp : users cannot create an order for a nonexistent customer
• Business-critical integrity constraint - rules vital to an organization's success and often require more insight and knowledge
• Exp  : Product returns are not accepted for fresh product 15 days after purchase

3.5 Increased Information Security

>  Information is an organizational asset and must be protected

>  Database 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. Can only read but cannot print/copy

4. Database management systems

>  DBMS - software through which users and application programs interact a database

4.1 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

4.2 Data-Driven Web Sites Business Advantages

• Development allows the web sites owner to make changes any time
• Content management a static site requires a programmer to makes updates
• Future expandability having a data-driven web site enables the site to grow faster than would be possible with a static site
• Minimizing human error have "error trapping" mechanisms to ensure that required information is filed out correctly
• Cutting production an update costs can be updated and "published" by any competent data entry or administrative person

5. Integrating Information among Multiple Database

>  Integration - allows separate systems to communication directly with each other

• Forward integration - take information entered into a given system and sends it automatically to all downstream systems and processes
• Backward integration - take information entered into a given system and sends it automatically to all upstream systems and processes

>  Building a central repository specifically for integrated information