Thursday, July 18, 2013

CHAPTER 7 -> Storing Organizational Information (Database)

relational database is a core, a system for storing and using data based upon the relationships among the elements of data. 

Different as databases may be in size, they are generally always structured according to one of three database models:

Relational = Nowadays, new installations of database management systems are almost exclusively of the relational type. Organizations that
already have a major investment in hierarchical or network technology
may add to the existing model, but groups that have no need to maintain
compatibility with “legacy systems” nearly always choose the relational
model for their databases.

Hierarchical = Hierarchical databases are aptly named because they have
a simple hierarchical structure that allows fast data access. They suffer
from redundancy problems and a structural inflexibility that makes database modification difficult.

Network = Network databases have minimal redundancy but pay for that
advantage with structural complexity.

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. 

We can think of dimensions as the entry points into the data or those business concepts we will use to slice and dice our data. In some organizations, dimensions are referred to as entities.

Many customers will buy many products in many stores at many times. We will call this type of data relationship a many-to-many relationship. In many-to-many relationships we use dimensional keys to organize the data. Look for the keys in the dimensional model at above.

-Each dimension has a single primary key. The primary key is unique to each row or record in our database and its value should not change over time.
-A primary key is often a consecutive or random number assigned to the record as it enters the database. 
-A primary key can also be made up of components of other fields in the table.
-The primary key is used for indexing the table to make it more efficient to search, sort, link and perform other operations on the data. 
-If we review the market dimension we find that each store key is unique. no two stores can have the same store key. Although it might seem that we could use store name as a unique means of identifying each store, we have  different stores with different addresses, states, regions, etc.

- When these keys appear in the fact table, they are referred to as foreign keys. In the Sales Fact Table, the foreign key is no longer unique. It may appear many times or not at all. 
- So the foreign keys in the fact table must have counterparts in the dimension tables to which it refers. This requirement of relational databases is called referential integrity.
- If you spend a great deal of time talking with data modelers you may come across a few more terms having to do with keys, such as composite keys and concatenated keys. Every fact table in a relational database has a composite key. 
- This is the primary key for the fact table and it is usually made up of a combination of the foreign keys maintained in the fact table. These foreign keys are concatenated (linked together into a single entry) into a primary key for the fact table.


customer can click faster and the other page can appear as far as possible.
this is an example of website that people can surfing the internet. Google, Mozilla, Explore and etc.
company want to integrate its database because they will connect,communicate,dealing and having relation with its customer everyday. Everyday its customers will open the webpage and search anything appear on the page. Therefore, if the product still available or not available the supplier must inform the customers immediately.Publish the information on the web page to make the customers realize that the product exist or not in the market. Then, when the customers got information they will not too disappointed and not waiting too long. Customers satisfy, the business relationship between sellers and customers will be good.:) 
increased flexibility      
increased information security   
 increased information integrity
reduced information redundancy
 increased scalability and performance


   - A Database Management System (DBMS) is a set of programs that enables you to store,modify, and extract information from a database.
- It also provides users with tools to add, delete, access, modify, and analyze data stored in one location.
-  A group can access the data by using query and reporting tools that are part of the DBMS or by using application programs specifically written to access the data. 
- DBMS also provide the method for maintaining the integrity of stored data, running security and users access, and recovering information if the system fails
- Many DBMS also include a graphics component that enables you to output information in the form of graphs and charts. Database and database management system are essential to all areas of business, they must be carefully managed.
Consider for example, a company selling sports cars. A database is created with information on each of its currently available cars e.g. make, model, engine details, year, a photograph, etc. A visitor to the website clicks on Porsche, the visitor enters the price range that they are interested in and hits 'Go'. The visitor is presented with information on available Porsche cars in their price range and an invitation to purchase or request more information from the company. The company has the ability to add new cars to the database, remove them or modify existing entries - this is achieved via a secure administration area on the website.


Data integration refers to the organization’s inventory of data and information assets as well as the tools, strategies and philosophies by which fragmented data assets are aligned to support business goals.

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