Answer:
Here is the Bank Account class:
public class Bank Account { //class definition
private String name; //private String type field to hold name
private double balance; // private double type field to hold balance
public Bank Account(String name, double balance) { // parameter constructor that takes
//this keyword is used to refer to the data members name and balance and to avoid confusion between name, balance private member fields and constructor arguments name, balance
this.name = name;
this.balance = balance; }
public void deposit(double amount) { //method to deposit amount
balance = balance + amount; } // adds the amount to the account causing the current balance to increase
public void withdraw(double amount) { //method to withdraw amount
balance = balance - amount; } //subtracts the amount causing the current balance to decrease
public String toString() { // to display the name and current balance
return name + " , $" + balance; } } //returns the name and the current balance separated by a comma and dollar
Explanation:
The explanation is provided in the attached document due to some errors in uploading the answer.
Solution :
Here, we need to perform JOIN operation of the students and registration.
Use NATURAL JOIN operator 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.