Which of the following is NOT a way to build on your strengths?

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

AVprozaik [17]

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.

6 0

3 years ago

_____ is a web application server that provides the ability to connect web servers to multiple data sources.

o-na [289]

ColdFusion/JRun is a web application server that provides the ability to connect web servers to multiple data sources.ColdFusion/JRun is an application server developed by Adobe, that is based on Sun Microsystems' Java 2 Platform, Enterprise Edition (J2EE). The other options are eliminated because: Ms Access is <span>Database Management System , FoxPro is database development system and dBase is also data management system.</span>

7 0

3 years ago

On a piano, a key has a frequency, say f0. Each higher key (black or white) has a frequency of f0 * rn, where n is the distance

Stels [109]

Answer:

#include <stdio.h>

int main()

{

float your_value1, your_value2, your_value3, your_value4, your_value5;

printf("Enter a frequency: ");

scanf_s("%f", &your_value1);//storing initial key frequency in your value 1

float r = 2.0 / 12;//typing 2.0 so it is treated as float and not int

your_value2 = your_value1 * r * 1; //initial*r*n

your_value3 = your_value1 * r * 2; //initial*r*n

your_value4 = your_value1 * r * 3; //initial*r*n

your_value5 = your_value1 * r * 4; //initial*r*n

printf("%0.2f %0.2f %0.2f %0.2f %0.2f", your_value1, your_value2, your_value3, your_value4, your_value5);

return 0;

}

Explanation:

The purpose of this exercise is to make you understand the difference between float and int. float variables are used when you need decimals in your calculations. int is used when you need integers. The problem in this exercise was the formulation of r. Now r is = 2/12, this means that when we type r as that, the computer assumes that it is an integer and treats it as such. So, it will convert the 0.166667 into 0. To overcome this, all you have to do is type 2.0 instead of 2 alone.

The %0.2 command restricts the float variable to 2 decimal places. By default, it has 6 decimal places.

I have used the function scanf_s instead of scanf simply because my compiler does not work with scanf.

3 0

3 years ago

Look at the slide.

svetlana [45]

Answer:

c

Explanation:

5 0

2 years ago

Read 2 more answers

Yuri is a skilled computer security expert who attempts to break into the systems belonging to his clients. He has permission fr

Tatiana [17]

Answer:

b) White-hat hacker

Explanation:

This is also called an ethical hacker. Unlike the other options, a white-hat hacker is a person specialized on computational security which offers services to organizations to test how safe they are from informatic attacks (viruses, theft of information, etc). This is carried out based on a agreement between the whihte-hat hacker and the client via a contract.

8 0

3 years ago