CHAPTER 7 -> Storing Organizational Information (Database)
1. FUNDAMENTAL CONCEPTS OF THE RELATIONAL DATABASE MODEL
A 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. 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.
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
2.THE ADVANTAGES OF RELATIONAL DATABASE
· > increased flexibility
· .> increased information security
· > increased information integrity
· >reduced information redundancy
· > increased scalability and performance
3.DATABASE MANAGEMENT SYSTEM & RELATIONSHIP WITH
WEBSITE
- 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.
4.WHY ORGANIZATION WOULD WANT TO INTEGRATE ITS DATABASE?
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.
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