Salam everone every monday i will keep goin to update about
information technology lately i so busy so the update lately will be
made after monday sorry...Now the update about the learning outcome in
chaptre 7....
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)
- 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.
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.
- PrimaryKey.....................................................................................................................................
- 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.
- ForeignKeys...................................................................................................................................
- 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 modellers 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. Evaluation the advantages of the relation databases model.
- Increased flexibility - can manipulated the information or present in many way and in the different shape.
- Increased scalability and performance - it will be happened in the organisation
- Reduced information redundancy
- the information will be sharing for many other people e.g, in
university condition, information about student need to shared with
other lecturer and staff about university.
- Increase information integrity (quality)
- information that get a similar source to spread the information
without the information will void from fraud and quality information is
liable.
- Increase information security - information that have quality and the security.
3. Define a databases management system and its relationship to a website
A databases management system is a software through which users and
application programs interact with a databases. The user send request
and performs the actual manipulation of the information in the
databases. Two primary ways can interact with databases management
system in terms of : a) directly b) indirectly
4. Explain why an organisation would to integrate its databases
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.
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
