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SIZIF [17.4K]
3 years ago
9

A(n) ____ is a service from local telephone companies in which up-to-date telephone facilities at the telephone company s centra

l (local) office are offered to business users, so that they don t need to purchase their own facilities.
Computers and Technology
1 answer:
dangina [55]3 years ago
3 0

Answer:

<em>Central Office Exchange Service</em>

Explanation:

Central Office Exchange Service, known as Centrex, is a service provided by  local U.S. telephone companies where up-to-date telephone services are provided  to company customers at the main (central) office of the phone company so they do  not need to buy their own services.

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I need the SQL statements for these questions:
zimovet [89]

Answer:

Explanation:

/* From the information provided, For now will consider the name of table as TRIPGUIDES*/

/*In all the answers below, the syntax is based on Oracle SQL. In case of usage of other database queries, answer may vary to some extent*/

1.

Select R.Reservation_ID, R.Trip_ID , C.Customer_Num,C.Last_Name from Reservation R, Customer C where C.Customer_Num=R.Customer_Num ORDER BY C.Last_Name

/*idea is to select the join the two tables by comparing customer_id field in two tables as it is the only field which is common and then print the desired result later ordering by last name to get the results in sorted order*/

2.

Select R.Reservation_ID, R.Trip_ID , R.NUM_PERSONS from Reservation R, Customer C where C.Customer_Num=R.Customer_Num and C.LAST_NAME='Goff' and C.FIRST_NAME='Ryan'

/*Here, the explaination will be similar to the first query. Choose the desired columns from the tables, and join the two tables by equating the common field

*/

3.

Select T.TRIP_NAME from TRIP T,GUIDE G,TRIPGUIDES TG where T.TRIP_ID=TG.TRIP_ID and TG.GUIDE_NUM=G.GUIDE_NUM and G.LAST_NAME='Abrams' and G.FIRST_NAME='Miles'

/*

Here,we choose three tables TRIP,GUIDE and TRIPGUIDES. Here we selected those trips where we have guides as Miles Abrms in the GUIDES table and equated Trip_id from TRIPGUIDES to TRIP.TRIP_Name so that can have the desired results

*/

4.

Select T.TRIP_NAME

from TRIP T,TRIPGUIDES TG ,G.GUIDE

where T.TRIP_ID=TG.TRIP_ID and T.TYPE='Biking' and TG.GUIDE_NUM=G.GUIDE_NUM and G.LAST_NAME='Boyers' and G.FIRST_NAME='Rita'

/*

In the above question, we first selected the trip name from trip table. To put the condition we first make sure that all the three tables are connected properly. In order to do so, we have equated Guide_nums in guide and tripguides. and also equated trip_id in tripguides and trip. Then we equated names from guide tables and type from trip table for the desired results.

*/

5.

SELECT C.LAST_NAME , T.TRIP_NAME , T.START_LOCATION FROM CUSTOMER C, TRIP T, RESERVATION R WHERE R.TRIP_DATE='2016-07-23' AND T.TRIP_ID=R.TRIP_ID AND C.CUSTOMER_NUM=R.CUSTOMER_NUM

/*

The explaination for this one will be equivalent to the previous question where we just equated the desired columns where we equiated the desired columns in respective fields and also equated the common entities like trip ids and customer ids so that can join tables properly

*/

/*The comparison of dates in SQL depends on the format in which they are stored. In the upper case if the

dates are stored in the format as YYYY-MM-DD, then the above query mentioned will work. In case dates are stored in the form of a string then the following query will work.

SELECT C.LAST_NAME , T.TRIP_NAME , T.START_LOCATION FROM CUSTOMER C, TRIP T, RESERVATION R WHERE R.TRIP_DATE='7/23/2016' AND T.TRIP_ID=R.TRIP_ID AND C.CUSTOMER_NUM=R.CUSTOMER_NUM

*/

6.

Select R.RESERVATION_ID, R.TRIP_ID,R.TRIP_DATE FROM RESERVATION R WHERE R.TRIP_ID IN

{SELECT TRIP_ID FROM TRIP T WHERE STATE='ME'}

/*

In the above question, we firstly extracted all the trip id's which are having locations as maine. Now we have the list of all the trip_id's that have location maine. Now we just need to extract the reservation ids for the same which can be trivally done by simply using the in clause stating print all the tuples whose id's are there in the list of inner query. Remember, IN always checks in the set of values.

*/

7.

Select R.RESERVATION_ID, R.TRIP_ID,R.TRIP_DATE FROM RESERVATION WHERE

EXISTS {SELECT TRIP_ID FROM TRIP T WHERE STATE='ME' and R.TRIP_ID=T.TRIP_ID}

/*

Unlike IN, Exist returns either true or false based on existance of any tuple in the condition provided. In the question above, firstly we checked for the possibilities if there is a trip in state ME and TRIP_IDs are common. Then we selected reservation ID, trip ID and Trip dates for all queries that returns true for inner query

*/

8.

SELECT G.LAST_NAME,G.FIRST_NAME FROM GUIDE WHERE G.GUIDE_NUM IN

{

SELECT DISTINCT TG.GUIDE_NUM FROM TRIPGUIDES TG WHERE TG.TRIPID IN {

SELECT T.TRIP_ID FROM TRIP T WHERE T.TYPE='Paddling'

}

}

/*

We have used here double nested IN queries. Firstly we selected all the trips which had paddling type (from the inner most queries). Using the same, we get the list of guides,(basically got the list of guide_numbers) of all the guides eds which were on trips with trip id we got from the inner most queries. Now that we have all the guide_Nums that were on trip with type paddling, we can simply use the query select last name and first name of all the guides which are having guide nums in the list returned by middle query.

*/

4 0
3 years ago
Can someone help me pz?
Katarina [22]
Yes definitely. now what do you need help with?
8 0
3 years ago
It is common for people to name directories as dir1, dir2, and so on. When there are ten or more directories, the operating syst
Vikki [24]

Answer:

Here the code is given as follows,

Explanation:

7 0
3 years ago
Question 2 In this question you are asked to calculate probabilties for the discrete uniform and exponential distribution. Make
sasho [114]

Answer:

Hi there! The question is asking to make changes to the H3_Q2.java program however there is no such program attached. Nevertheless, the requirements in the question can be addressed in a new H3_Q2.java program that i've listed below.

Explanation:

We can use the Scanner util in Java for prompting user input. The method nextInt() and nextDouble() allow only values of types "int" and "double" respectively. I have used the "switch" statement to direct the program based on user selection of menu item. The checks are printed with the "System.out.println" command and the program exits in case of error or invalid input. Finally, the calculation of probability simply requires you to replace the comment with the formula for the probability calculation based on the method chosen.

H3_Q2.java

import java.util.Scanner;

public class H3_Q2 {

 public static void main(String args[]) {

   // print main menu for user selection

   System.out.println("Please type 1 to select 'discrete uniform' or 2 to select 'exponential'");

   Scanner scan = new Scanner(System.in);

   int selection = scan.nextInt();

   switch(selection) {

     case 1:

       // discrete uniform

       System.out.println("Please enter a lower bound value a: ");

       int a = scan.nextInt();

       System.out.println("Please enter a upper bound value b: ");

       int b = scan.nextInt();

       System.out.println("Please enter a value x: ");

       int x = scan.nextInt();

       if (b <= a) {

         System.out.println("The upper bound value b should be greater than the lower bound value a");

         System.exit(0);

       }

       if (a > x) {

         System.out.println("The value x should be greater than the lower bound value b");

         System.exit(0);

       }

       if (b < x) {

         System.out.println("The value x should be greater than the lower bound value b");

         System.exit(0);

       }

       break;

     case 2:

       // exponential

       System.out.println("Please enter a lambda value for exponential: ");

       double lambda = scan.nextDouble();

       System.out.println("Please enter a value x: ");

       double d_x = scan.nextDouble();

       if (d_x <= 0.0) {

         System.out.println("The value x should be greater than 0");

         break;

       } else {

         // calculate P(X = x) and P(X ≤ x)

         // result = calculateExponential()

         System.out.println("The calculation for the exponential method given the lambda value " + lambda + " and the value of x " + d_x + " is: ");

       }

       break;

     default:

       System.out.println("Invalid input. Exiting..");

       break;

   }

 }

}

7 0
3 years ago
When a cardholder successfully contests a charge, the acquiring bank must retrieve the money it placed in the merchant account i
lions [1.4K]

Answer:

Charge back.

Explanation:

A chargeback is a charge that is returned to a payment card after a customer successfully disputes an item on their account transactions report. Simply put, it is the reversal of a credit card payment that comes directly from the bank.

Most commonly the payer is a consumer.

A chargeback may occur on bank accounts or credit cards. They can be granted to a cardholder for a variety of reasons. A chargeback can be considered a refund since it returns specified funds taken from an account through a prior purchase. Chargebacks are focused on charges that have been fully processed and settled. Chargebacks can often take several days for full settlement as they must be reversed through an electronic process involving multiple entities.

The chargeback is ordered by the bank that issued the consumer's payment card.

6 0
3 years ago
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