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)
Specify the foreign keys for the above schema, stating any assumptions you make. Then specify the following queries in relational algebra:
a. Give the details (all attributes of TRIP relation) for trips that exceeded $2000 in expenses.
b. Print the SSN of salesman who took trips to ‘Honolulu'.
c. Print the total trip expenses incurred by the salesman with SSN = ‘234-56-7890'