Question given relation r (A,B,C,D) and the following fd’s. Identify the candidate key for r and highest normal form b->C, d->a question Consider the universal relation R= {A,



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EMP_ID

EMP_NAME

EMP_PHONE

EMP_STATE

14

John

1122336665,
4598346521

UP

20

Harry

9878112233

Bihar

12

Sam

1122778844
98453300111,

Punjab

The decomposition of the EMPLOYEE table into 1NF has been shown below:

EMP_ID

EMP_NAME

EMP_PHONE

EMP_STATE

14

John

1122336665

UP

14

John

4598346521

UP

20

Harry

9878112233

Bihar

12

Sam

1122778844

Punjab

12

Sam

98453300111

Punjab


Question 1

Translate the following: i) Key constraints ii) Integrity constraints. 
i) Key constraints





ii) Integrity constraints



Question 4

Determine the normal Form of given Relation

R(ABCDE)

FDs are: AB-> C, C-> D, D-> E, E-> A, D-> B



Question 3

Mention different types of Security levels.
There are three layers of database security:

  • the database levels

Security at the database level occurs within the database itself, where the data live.

  • the access levels

Access layer security focuses on controlling who is allowed to access certain data or systems containing it.

Database security at the perimeter level determines who can and cannot get into databases. Each level requires unique security solutions.


 

Importance of Security in Database Environment


Database security is the protection of the database against intentional and unintentional threats that may be computer-based or non-computer-based. Database security is the business of the entire organization as all people use the data held in the organization’s database and any loss or corruption to data would affect the day-to-day operation of the organization and the performance of the people. Therefore, database security encompasses hardware, software, infrastructure, people and data of the organization.

Question 4

We cannot guarantee that BCNF relation schema will be produced by dependency preserving decomposition of non-BCNF relation schema. Give the counter example to illustrate this point


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