1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Ainat [17]
3 years ago
6

[1] Please find all the candidate keys and the primary key (or composite primary key) Candidate Key: _______________________ Pri

mary Key: ____________________________ [2] Please find all the functional dependencies ________________________________________________ _________________________________________________ __________________________________________________ _____________________________________________________ [3] Please find out the second normal form (in relational schema). [4] Please find out the third normal form.
Computers and Technology
1 answer:
AVprozaik [17]3 years ago
6 0

Answer:

Check the explanation

Explanation:

1. The atomic attributes can't be a primary key because the values in the respective attributes should be unique.

So, the size of the primary key should be more than one.

In order to find the candidate key, let the functional dependencies be obtained.

The functional dependencies are :

Emp_ID -> Name, DeptID, Marketing, Salary

Name -> Emp_ID

DeptID -> Emp_ID

Marketing ->  Emp_ID

Course_ID -> Course Name

Course_Name ->  Course_ID

Date_Completed -> Course_Name

Closure of attribute { Emp_ID, Date_Completed } is { Emp_ID, Date_Completed , Name, DeptID, Marketing, Salary, Course_Name, Course_ID}

Closure of attribute { Name , Date_Completed } is { Name, Date_Completed , Emp_ID , DeptID, Marketing, Salary, Course_Name, Course_ID}

Closure of attribute { DeptID, Date_Completed } is { DeptID, Date_Completed , Emp_ID,, Name, , Marketing, Salary, Course_Name, Course_ID}

Closure of attribute { Marketing, Date_Completed } is { Marketing, Date_Completed , Emp_ID,, Name, DeptID , Salary, Course_Name, Course_ID}.

So, the candidate keys are :

{ Emp_ID, Date_Completed }

{ Name , Date_Completed }

{ DeptID, Date_Completed }

{ Marketing, Date_Completed }

Only one candidate key can be a primary key.

So, the primary key chosen be { Emp_ID, Date_Completed }..

2.

The functional dependencies are :

Emp_ID -> Name, DeptID, Marketing, Salary

Name -> Emp_ID

DeptID -> Emp_ID

Marketing ->  Emp_ID

Course_ID -> Course Name

Course_Name ->  Course_ID

Date_Completed -> Course_Name

3.

For a relation to be in 2NF, there should be no partial dependencies in the set of functional dependencies.

The first F.D. is

Emp_ID -> Name, DeptID, Marketing, Salary

Here, Emp_ID -> Salary ( decomposition rule ). So, a prime key determining a non-prime key is a partial dependency.

So, a separate table should be made for Emp_ID -> Salary.

The tables are R1(Emp_ID, Name, DeptID, Marketing, Course_ID, Course_Name, Date_Completed)

and R2( Emp_ID , Salary)

The following dependencies violate partial dependency as a prime attribute -> prime attribute :

Name -> Emp_ID

DeptID -> Emp_ID

Marketing ->  Emp_ID

The following dependencies violate partial dependency as a non-prime attribute -> non-prime attribute :

Course_ID -> Course Name

Course_Name ->  Course_ID

So, no separate tables should be made.

The functional dependency Date_Completed -> Course_Name has a partial dependency as a prime attribute determines a non-prime attribute.

So, a separate table is made.

The final relational schemas that follows 2NF are :

R1(Emp_ID, Name, DeptID, Marketing, Course_ID, Course_Name, Date_Completed)

R2( Emp_ID , Salary)

R3 (Date_Completed, Course_Name, Course_ID)

For a relation to be in 3NF, the functional dependencies should not have any transitive dependencies.

The functional dependencies in R1(Emp_ID, Name, DeptID, Marketing, Date_Completed) is :

Emp_ID -> Name, DeptID, Marketing

This violates the transitive property. So, no table is created.

The functional dependencies in R2 (  Emp_ID , Salary) is :

Emp_ID -> Salary

The functional dependencies in R3 (Date_Completed, Course_Name, Course_ID) are :

Date_Completed -> Course_Name

Course_Name   ->  Course_ID

Here there is a transitive dependency as a non- prime attribute ( Course_Name ) is determining a non-attribute ( Course_ID ).

So, a separate table is made with the concerned attributes.

The relational schemas which support 3NF re :

R1(Emp_ID, Name, DeptID, Course_ID, Marketing, Date_Completed) with candidate key as Emp_ID.

R2 (  Emp_ID , Salary) with candidate key Emp_ID.

R3 (Date_Completed, Course_Name ) with candidate key Date_Completed.

R4 ( Course_Name, Course_ID ).  with candidate keys Course_Name and Course_ID.

You might be interested in
___________ key encryption in wep uses the rc4 encryption algorithm.
lora16 [44]

Shared key encryption in wep uses the rc4 encryption algorithm.

7 0
2 years ago
Encapsulation is the process of “packaging” information prior to transmitting it from one location to another. true or false
GenaCL600 [577]

The statement that encapsulation is the process of “packaging” information prior to transmitting it from one location to another is true.

This method augments the data with successive layers of control information before transmission across a network. Each OSI (Open System Interconnection) layer  is part of the encapsulation by adding a header to the data packet in the transmission network.

3 0
3 years ago
Which terms means device that converts one voltage to another ?
Jet001 [13]

Answer:

I believe it is an adapter

Explanation:

An adapter or adaptor is a device that converts attributes of one electrical device or system to those of an otherwise incompatible device or system. Some modify power or signal attributes, while others merely adapt the physical form of one connector to another.

6 0
2 years ago
Elena is used to kissing her friends on both cheeks as a form of greeting in her native country. She notices that her new friend
Veseljchak [2.6K]

Answer:

c. Norms.

Explanation:

When Elena noticed her friend getting uncomfortable when she kisses him on the cheeks as a form of greeting she was violating his norms.

Norms are something that is standard or typical.

In USA there they not used to kiss on the cheeks to greet their friends there would be some other norm of greeting someone.

5 0
3 years ago
What is a unit to measure loudness
FinnZ [79.3K]

decibels i believe is the correct answer. hope it helps :)

3 0
3 years ago
Other questions:
  • What piece of software tells the operating system how to use a specific hardware device?
    14·1 answer
  • Given two double variables, best value and second best value, write some code that swaps their values. declare any additional va
    13·1 answer
  • Analyzing Uses for PDFs
    6·1 answer
  • Select the correct answer.
    5·1 answer
  • When targeting customers of the consumer population at market a product, what type of segmentation information would be most hel
    12·2 answers
  • A network systems administrator would most likely help with
    13·2 answers
  • Yall like portal 1 or 2
    8·1 answer
  • Which memory can be removed from motherboard? RAM OR ROM?​
    11·1 answer
  • A(n) ________ cloud does not free an organization from the issues associated with managing the cloud infrastructure, but it does
    7·1 answer
  • What are three ways of verifying legitimate right of access to a computer system?
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!