$4.$ Consider the following schema for a database that keeps

information about business trips and their associated expenses by

employees, noting that SSN is a foreign key in Trip that refers to

Employee, and TripId is a foreign key in Expense that refers to Trip;

Employee$($SSN$,$ name, deptNo, jobTitle, salary$)$

Trip$($tripId$,$ departureCity, destinationCity, departureDate, returnDate,

SSN$)$

Expense$($tripId$,$ item, date, amount$)$

Write relational algebra queries for each of the following:

a$.$ Get a list of all the different destination cities where the

employees have taken trips.

b$.$ Find all the employee information for employees who work in

Department $10.$

c$.$ Get complete trip records $($but not their associated expenses$)$ for

all trips with departure dates after January $1$ of the current year.

d$.$ Find the names of all employees who have departed on trips from

London.

e$.$ Find the SSN of all employees who have any single expense item

of more than $$1,000$ for any trip.

f$.$ Find the names of all employees who have any expense item

called $$Entertainment$.$

g$.$ Find the destination cities of all trips taken by employees who

have the job title of $$Consultant$.$

h$.$ Find the names and departments of all employees who have any

single expense item of over $$1,000$ since January $1$ of this year.

i$.$ Find the items and amounts of all expenses for a trip to Cairo

beginning on January $3$ of this year taken by employee Jones.

j$.$ Find the names, departments, and job titles of all employees who

have any expense item with value $$Service Charge$$ for trips taken

to Melbourne last year, along with the date and amount of the

expense.