Specify the following queries in relational algebra on the database schema given in Exercise 5.15:

Exercise 5.15

Consider the following relations for a database that keeps track of business trips of salespersons in a sales office:

SALESPERSON(Ssn, Name, Start_year, Dept_no)

TRIP(Ssn, From_city, To_city, Departure_date, Return_date, Trip_id)

EXPENSE(Trip_id, Account#, Amount)

A trip can be charged to one or more accounts. Specify the foreign keys for this schema, stating any assumptions you make.

a. Give the details (all attributes of trip relation) for trips that exceeded $2,000 in expenses.

b. Print the Ssns of salespeople who took trips to Honolulu.

c. Print the total trip expenses incurred by the salesperson with SSN = ‘234-56-7890’.