You are given the task of designing

a database for a travel agency called TRAVEL$-$BEST. Read the following description and draw its

ER diagram.

In TRAVEL$-$BEST, there are two types of customers: individual customers and corporate

customers. A customer must be either an individual customer or corporate customer; no other

customer types are allowed. For both types of customers, TRAVEL$-$BEST keeps track of their

customer ID $($unique$),$ customer name, phone number, and address. In addition:

$$ Corporate customers have an account number and several staff members, where each staff

member has a name and a phone number.

$$ Individual customers have a cell phone number and name. Plus, each individual customer

may have saved several credit cards, but a credit card is saved by at most one customer. Each

credit card has a name, expiration date, and a unique card number. $($Hint: Make credit card

a weak entity.$)$

A customer can make several reservations. Each reservation is made by at most one customer.

A reservation has a reservation date, a reservation platform $($could be web, mobile, phone, etc.$)$

and a unique reservation ID$.$

A reservation contains several flights. The same flight can be contained in multiple reservations.

A flight has an origin, a destination, and a unique flight number.

Finally, individual customers rate flights. $($Important: Corporate customers do not rate flights!$)$

An individual customer can rate many flights and a flight can be rated by many individual customers. The rating value must be stored in the database.