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1. Discuss the importance of data modeling. In your narrative you must discuss the following

areas: How are data models used in practice? What about conceptual models?

Common data modeling notations. (30 marks)

Data model is a relatively simple representation, usually graphical, of a more complex real

world object event. The data model’s main function is to help us understand the complexities of

the real-

world environment. The database designer uses data models to facilitate the interaction amongde

signers, application programmers, and end users. In short, a good data model is a

communications

device that helps eliminate (or at least substantially reduce) discrepancies between the database

design’s components and the real world data environment. The development of data

models, bolstered by powerful database design tools, has made it possible to substantially dimini

sh thedatabase design error potential. (Data modeling is the act of exploring data-oriented

structures and can be used for a variety of purposes, from high-level conceptual models to

physical data models. It is a great communication tool because they facilitate interaction andcommunication between the designers. From the point of view of an object oriented developer

data modeling is conceptually similar to class modeling. With data modeling you identify entity

types whereas with class modeling you identify classes.

Data modelers often use multiple models to view the same data and ensure that all processes,

entities, relationships and data flows have been identified. There are several different approaches

to data modeling, including: In order to better understand data models you need to know how

they are used in practice. There are three basic styles of data model, the conceptual, logical and

physical. Conceptual data models, sometimes called domain data models, are typically used to

explore domain concepts with project stakeholders. On agile teams high level conceptual models

are often created as part of your initial requirements envisioning efforts as they are used toexplore the high level static business structures and concepts. On traditional teams conceptual

data models are often created as the precursor to LDM (logical data model) or as alternatives.

Logical data models are used to explore domain concepts, and their relationships, of your

problem domain and this can be done for the scope of a single project or the entire enterprise.

LDMs depict the logical entity types, the data attributes describing those entities, and the

relationship between the entities.

Physical data models (PDMs) are used to design the internal schema of a database, depicting

the data tables, data columns of those tables and relationships between the tables. PDMs often

prove to be useful on both Agile and traditional projects.

Halpin (2001) points out that many data professionals prefer to create an Object-Role Model

(ORM), an example is depicted in the figure below, instead of an LDM for a conceptual model.

The advantage is that the notation is very simple, something your project stakeholders can

quickly grasp, although the disadvantage is that the models become large very quickly. ORMs

enable you to first explore actual data examples instead of simply jumping to a potentially

incorrect abstraction.



There are basically four common data modeling notations: Information Engineering (IE), Barker,

IDEF1X, and the Figure 4 below presents a summary of the syntax of four common data

modeling notations: Information Engineering (IE), Unified Modeling Language (UML). The IE

notation is a simple and easy to read, and is well suited for high level logical and enterprise data

modeling. The only drawback is that is does not support the identification of attributes of an

entity. However the Barker notation is one of the more popular ones, it is supported by Oracle’s

toolset, and is well suited for all types of data models..Its approach to sub typing can become

clunky with hierarchies that go several levels deep. With IDEF1K, this notation is overly

complex, it was originally intended for physical modeling but has misapplied for logical

modeling as well and finally the UML , this is not an official data modeling notation yet,

although several suggestions for data modeling profile for the UML exists, none are complete

and more importantly are not “official” UML yet.

2. What is a table and what role does it play in the relational data model. In your discussion youneed to identify and relate the following: How to model data

Identify entity types, Identify attributes, Apply naming conventions, Identify relationships,

Apply data model patterns, Assign keys and data redundancy. Where applicable provide

examples. (30 marks)

Strictly speaking, the relational data model bases data storage on

relations

. These relations are basedon algebraic set theory. However, the user perceives the relations to be

tables. In the relationaldatabase environment, designers and users

perceive

a table to be a matrix consisting of a series of row/column intersections.Tables, also calledrelations, are related to each other by sharing a commonentity characteristic. For example, an

INVOICE table would contain a customer number that points tothat same number in the

CUSTOMER table. This feature enables the RDBMS to link invoices to thecustomers who

generated them.Tables are especially useful from the modeling and implementation

perspecectives. Because tablesare used to describe the entities they represent, they provide ane

asy way to summarize entitycharacteristics and relationships among entities. And, because

they are purely conceptual constructs,the designer does not need to be concerned about the

physical implementation aspects of the databasedesign

3. Identify the different types of databases. What are the main components of a database system?

(20 marks)



3/ Continuing developments in information technology and its business applications have

resulted in the evolution of several major types of databases. Several major conceptual categories

of databases that may be found in computer-using organizations include:

Operational Databases

The databases store detailed data needed to support the operations of the entire organization.

They are also called subject area databases (SADB), transaction databases, and production

databases: Examples are customer databases, personnel databases, inventory databases, and other

databases containing data generated by business operations

Distributed Databases

Many organizations replicate and distribute copies or parts of databases to network

sewers at a variety of sites. These distributed databases can reside on network servers

on the World Wide Web, on corporate Intranets or extranets, or on other company networks.

Distributed databases may be copies of operational or analytical. databases,

hypermedia or discussion databases, or any other type of database. Replication and distribution

of databases is done to improve database performance and security.External Databases

Access to external, privately owned online databases or data banks is available for a fee to

end users and organizations from commercial online services, and with or without charge from

many sources on the Internet, especially the Web.

Hypermedia Databases

It consists of hyperlinked pages of multimedia (text, graphics, and photographic images,

video clips, audio segments, etc.). From a database management point of view, the set of

interconnected multimedia pages at a website is a database of interrelated hypermedia page

elements, rather than interrelated data records.

A database system has four components. These four components are important for understanding and designing the database system. These

are:

1. Data

2. Hardware

3. Software

4. Users

1. Data

As we have discussed above, data is raw hand information collected by us. Data is made up

of data item or data aggregate. A Data item is the smallest unit of named data: It may consist of

bits or bytes. A Data item is often referred to as field or data element. A Data aggregate is the

collection of data items within the record, which is given a name and referred as a whole. Data

can be collected orally or written. A database can be integrated and shared. Data stored in a

system is partition into one or two databases. So if by chance data lost or damaged at one place,

then it can be accessed from the second place by using the sharing facility of data base system.

So a shared data also cane be reused according to the user’s requirement. Also data must be in



the integrated form. Integration means data should be in unique form i.e. data collected by using

a well-defined manner with no redundancy, for example Roll number in a class is non-redundant

form and so these have unique resistance, but names in class may be in the redundant form and

can create lot of problems later on in using and accessing the data.

2. Hardware

Hardware is also a major and primary part of the database. Without hardware nothing can be

done. The definition of Hardware is “which we can touch and see”, i.e. it has physical existences.

All physical quantity or items are in this category. For example, all the hardware input/output

and storage devices like keyboard, mouse, scanner, monitor, storage devices (hard disk, floppy

disk, magnetic disk, and magnetic drum) etc. are commonly used with a computer system.

3. Software

Software is another major part of the database system. It is the other side of hardware.

Hardware and software are two sides of a coin. They go side by side. Software is a system.

Software are further subdivided into two categories, First type is system software (like all the

operating systems, all the languages and system packages etc.) and second one is an applicationsoftware (payroll, electricity billing, hospital management and hostel administration etc.). We

can define software as which we cannot touch and see. Software only can execute. By using

software, data can be manipulated, organized and stored. -

4. Users

Without user all of the above said components (data, hardware & software) are meaning less.

User can collect the data, operate and handle the hardware. Also operator feeds the data and

arranges the data in order by executing the software. Other components

1. People - Database administrator; system developer; end user.

2. CASE tools: Computer-aided Software Engineering (CASE) tools.

3. User interface - Microsoft Access; PowerBuilder.4. Application Programs - PowerBuilder script language; Visual Basic; C++; COBOL.

5. Repository - Store definitions of data called METADATA, screen and report formats,

menu definitions, etc.

6. Database - Store actual occurrences data.

7. DBMS - Provide tools to manage all of this - create data, maintain data, control security

access to data and to the repository, etc.

4/ Create an ERD Diagram for an asset management system for small business to keep records

of asset management and assets consisting of at least eight entities. Show full relationships and

attributes and multiplicities using the Crow’s Foot Notation. (20 marks)



Sousa, S. d. (2009 ). Different Types of Database. 2009 My-Project-Management-Expert.

University, T. P. (2008 ). Types of Database Management Systems . Retrieved from

http://www.personal.psu.edu/glh10/ist110/topic/topic07/topic07_06.html.

W.Ambler, S. (2011). Data Modeling 101. Retrieved from

http://www.agiledata.org/essays/dataModeling101.html.

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