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maxonik [38]
3 years ago
9

Consider the relational schema below: Students(sid: integer, sname: string, major: string) Courses(cid: integer, cname: string,

hours: integer) Enrollment(sid: integer, cid: integer, grade: real) Write a relational algebra expression that satisfies this query? Find the distinct names of all students that take at least three courses and major in "Philosophy".
Computers and Technology
1 answer:
daser333 [38]3 years ago
7 0

Solution :

Here, we need to perform JOIN operation of the students and registration.

Use NATURAL JOIN operator \Join and so no need to specify Join condition.

Also we need to selection operator tp select only those course whose major in "philosophy".

Finally we projection operator π to project only distinct students name who took at least three courses.

$\pi [\sigma_{\text{student's nam}e} [ \sigma(\text{three courses}) \Join \text{"Philosophy"}]]$

You might be interested in
The ArrayList class contains a trim method that resizes the internal array to exactly the capacity. The trim method is intended
andreev551 [17]

Answer:

public void trimToSize() {

modCount++;

if (size < elementData.length) {

elementData = (size == 0)

? EMPTY_ELEMENTDATA

: Arrays.copyOf(elementData, size);

}

}

Now, the running time for copyOf() function is O(N) where N is the size/capacity of the ArrayList. Hence, the time complexity of trimToSize() function is O(N).

Hence, the running time of building an N-item ArrayList is O(N^2).

Please find the sample code below.

CODE

==================

import java.util.ArrayList;

public class Driver {

  public static void main(String[] args) throws Exception{

      int N = 100000;

      ArrayList<Integer> arr = new ArrayList<>(N);

     

      long startTime = System.currentTimeMillis();

      for(int i=0; i<N; i++) {

          arr.add(i);

          arr.trimToSize();

      }

      long endTime = System.currentTimeMillis();

      double time = (endTime - startTime)/1000;

      System.out.println("Total time taken = " + time + " seconds.");

  }

}

Explanation:

5 0
4 years ago
Problem Statement − Suppose the problem statement at hand is to contain the attrition that happens in companies worldwide. High
Tju [1.3M]

Answer:Analysis is derived from the Greek word ‘analusis’, which translates into ‘breaking up’ in English. Analysis is older than the times of great philosophers like Aristotle and Plato. As discussed in the previous section, analysis is the process of breaking down a big single entity into multiple fragments. It is a deduction where a bigger concept is broken down to smaller ones. This breaking down into smaller fragments is necessary for improved understanding.

So, how does analysis help in design thinking? During analysis, design thinkers are required to break down the problem statement into smaller parts and study each one of them separately. The different smaller components of the problem statement are to be solved one-by-one, if possible. Then, solutions are thought for each of the small problems. Brainstorming is done over each of the solutions.

Later, a feasibility check is done to include the feasible and viable solutions. The solutions that don’t stand firm on the grounds of feasibility and viability are excluded from the set of solutions to be considered.

Design thinkers are, then, encouraged to connect with the diverse ideas and examine the way each idea was composed. This process of breaking down the bigger problem statement at hand into multiple smaller problem statements and examining each as a separate entity is called analysis.

Reductionism

The underlying assumption in analysis is reductionism. Reductionism states that the reality around us can be reduced down to invisible parts. The embodiment of this principle is found in basic axioms of analytic geometry, which says “the whole is equal to the sum of its parts”. However, understanding of a system cannot be developed by analysis alone. Hence, synthesis is required following analysis.

Synthesis

Synthesis refers to the process of combining the fragmented parts into an aggregated whole. It is an activity that is done at the end of the scientific or creative inquiry. This process leads to creation of a coherent bigger entity, which is something new and fresh. How does synthesis come into picture in design thinking?

Once the design thinkers have excluded the non-feasible and non-viable solutions and have zeroed-in on the set of feasible and viable solutions, it is time for the thinkers to put together their solutions.

Out of 10 available solutions, around 2-3 solutions may need to be excluded since they may not fit into the larger picture, i.e. the actual solution. This is where synthesis helps.

The design thinkers start from a big entity called the problem statement and then end up with another bigger entity, i.e. the solution. The solution is completely different from the problem statement. During synthesis, it is ensured that the different ideas are in sync with each other and do not lead to conflicts.

Analysis + Synthesis = Design Thinking

Analysis and synthesis, thus, form the two fundamental tasks to be done in design thinking. Design thinking process starts with reductionism, where the problem statement is broken down into smaller fragments. Each fragment is brainstormed over by the team of thinkers, and the different smaller solutions are then put together to form a coherent final solution. Let us take a look at an example.

Analysis Synthesis

Case Study

Problem Statement − Suppose the problem statement at hand is to contain the attrition that happens in companies worldwide. High quality employees leave the organization, mainly after the appraisal cycle. As a result, an average company loses its valuable human resources and suffers from overhead of transferring the knowledge to a new employee. This takes time and additional human resource in the form of a trainer, which adds to the company’s costs. Devise a plan to contain attrition in the company.

Analysis − Now, let’s break down the problem statement into various constituent parts. Following are the subparts of the same problem statement, broken down to elementary levels.

The employees are not motivated anymore to work in the company.

Appraisal cycle has something to do with attrition.

Knowledge transfer is necessary for new employees.

Knowledge transfer adds to the cost of the company.

Synthesis − Now, let's start solving each problem individually. In this step, we will do synthesis. Let's look at one problem at a time and try to find a solution only for that problem statement, without thinking of other problem statements.

Explanation:

6 0
3 years ago
How do you find binary?
trasher [3.6K]

Answer:

To convert integer to binary, start with the integer in question and divide it by 2 keeping notice of the quotient and the remainder. Continue dividing the quotient by 2 until you get a quotient of zero. Then just write out the remainders in the reverse order.

Explanation:

3 0
3 years ago
Explain what will happen if we continue to use fossil fuels at the rate we are now and what impacts it will have on the planet.
Westkost [7]

Answer:

At the point when non-renewable energy sources are singed, they discharge carbon dioxide and other ozone depleting substances, which thusly trap heat in our air, making them the essential supporters of an Earth-wide temperature boost and environmental change. At the point when we consume oil, coal, and gas, we don't simply meet our vitality needs—we drive the current an unnatural weather change emergency also. Non-renewable energy sources produce huge amounts of carbon dioxide when consumed. Carbon discharges trap heat in the air and lead to environmental change.

7 0
4 years ago
You want to get an average of the number of siblings people in a group have. Which data format would be best for you to receive?
never [62]

The data format would be best for you to receive is Spreadsheet.

<h3>What is spreadsheet?</h3>

A spreadsheet is a computer program that allows you to compute, organize, analyze, and store data in tabular form. Spreadsheets were created as electronic counterparts to paper accounting spreadsheets. The software runs on data entered into table cells. Each cell can include numeric or text data, as well as the results of formulas that calculate and display a value dependent on the contents of other cells. One such electronic document may also be referred to as a spreadsheet.

Spreadsheet users can change any recorded value and see how it affects calculated numbers. Because of this, the spreadsheet is ideal for "what-if" analysis because many situations may be studied quickly without human recalculation. Modern spreadsheet software can include numerous interacting sheets and display data as text and numbers or as graphics.

To learn more about spreadsheet visit:

brainly.com/question/8284022

#SPJ4

6 0
2 years ago
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