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vichka [17]
3 years ago
7

What purpose would tracking changes be most useful for?

Computers and Technology
1 answer:
olya-2409 [2.1K]3 years ago
6 0
So, you can be able to make a prediction and understand the cycle.
You might be interested in
[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
The expressions in each part of an AND or OR expression use ________ evaluation; that is, they are evaluated only as much as nec
I am Lyosha [343]

Answer:

The expressions in each part of an AND or OR expression use <u>Short Circuit</u> evaluation; that is, they are evaluated only as much as necessary to determine whether the entire expression is true or false.

Explanation:

Logic operations follow different type of evaluation methods that can be short circuit or open circuit evaluation. In short circuit evaluation if first operand of the expression is true or false in OR or AND operation respectively, the result will found as true or false without checking the second operand of the expression. This is called Short Circuit Evaluation.

In OR operation, If first operand is true it means that the result of the expression is true without knowing that the other operand is true or false. In AND operation, If the first operand is False, the result will found as False without knowing that whether the 2nd operand is  true or false.

This Mechanism is called Short Circuit Evaluation.

4 0
3 years ago
During her presentation, Marie wanted more freedom to move about the room and interact with her audience. She can use _____.
S_A_V [24]

Answer:

The correct answer is:

"a laser pointer and a remote control"

Explanation:

Let us look at the options one by one.

notes pages and an LCD projector

When she is using these options, she cannot have the freedom to move as she has to operate the projector somehow.

laptop computer and a pointer

In this case she has to operate laptop so movement will be reduced.

<u>A laser pointer and remote control</u> will give her a lot of freedom to move as she can use the remote control to operate the slides and the pointer to point stuff ont the slides.

Hence,

The correct answer is:

"a laser pointer and a remote control"

5 0
3 years ago
Site won't let me log in and is glitching? Is rainly down?
yarga [219]

Answer: Somewhat.

Explanation: Try refreshing your pages, or reopening your browser.

3 0
3 years ago
Read 2 more answers
Shaniya has misspelled a scientific name in her biology report. She needs to correct it, but she has no access to a computer. Sh
Sav [38]

Answer:

Selection of answers:

Yes, she can navigate the window and do simple editing.

Yes, she can use this application for free and navigate the window.

No, her document is “Read-Only,” so she cannot navigate the window.

No, her application has limited features and she cannot access the document.

Answer is: No, her document is “Read-Only,” so she cannot navigate the window.

3 0
3 years ago
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