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CS242 – DBMS

Assignment no. 1

Leandro M. Santos CS241 DBMS

BSCS 2nd

Year Friday4:00pm-6:00pm

What is a database?

“Database is a collection of organized (structured) and logically related data to serve a purpose.“ 

What is the difference of database Management System from Database?

The meaning of database was mentioned earlier in this page, in order to differentiate database fromDBMS we will define what DBMS is:

“A database management system (DBMS), sometimes just called a database manager, is a program that

provides users access to data in a database. DBMS ensures the integrity and security of the data while

providing an organized way of inputting data, data retrieval, and maintenance and report generation.

DBMS enables data sharing among multiple applications. A DBMS is quite similar to a file manager.

The most popular DBMS is a relational database management system; however, a newer kind of DBMS

called Object-Oriented Database Management System (ODBMS) exist. There are some databases that

are combination of relational (RDBMS) and Object-oriented (ODBMS) database management system.

What is the difference of information model and data model?

Information model focuses on the conceptual stage of development. Information model defines the

relationship between entities. Information model hides some implementations and protocols to simplify

the presentation depending on the needs of the designer. Data model on the other hand focuses on

how the data is stored and accessed (data structure). An information model can have different data

model. Data model is more detailed compared to an information model. These models are used by

members of a team with different discipline to communicate an idea in a singular way.

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CS242 – DBMS

Assignment no. 1

Four different types of data model:

The four different types of data models are Enterprise, Conceptual, Logical and Physical model. Let us

define each:

1.  Enterprise Model defines the entities and general processes occurring in an organization. Itprovides an overview of all the big processes of an organization. Entity relationship and business

rules are clearly defined. ER diagram is best used at this model.

2.  Conceptual Model is the detailed specification of overall structure of that is independent of 

database management technology.

3.  Logical Model is the representation of data for a type of data management technology.

4.  Physical Model describes how logical model are stored in the secondary memory by a specific

database management system.

How do you define business rules?

Business rules are set restrictions or constrain set by an institution to be followed by its employees and

clients alike. There are no standard set of business rules and these rules are unique in each institution.

Business rules change according to the current needs of the organization and the slightest changes can

create huge impact on the system and interface.

An example of business rule is “No student shall enroll a section in a class if he/she has not finished the

prerequisite subjects”. Another example would be, “All students without exception shall be provided

with student number”. The rules mentioned above will directly reflect on the database design. However

not all business rules are important in designing a database, an example is “Friday shall be Casual Dress

code Day” or “No student is allowed to attend class without wearing complete uniform.”