(total marks 20) Given the same simple Customer-Subscribesto_Phonecompany database schema you worked on in Assignment 1, which contains three files describing information about telephone company subscribers as follows Customer (SSN: integer, CName: string, Caddress: string, balance: real) Subscribesto (SSN: integer, Compld: string, phonetype: string, month: string, billamt: real) PhoneCompany (Compld: string, CompName: string, Address: string, Numproducts:integer]) Note SSN, CName, Caddress and balance stand for the customer's social security number, name, address and phone bill balance owing respectively. Also, Compld, phonetype, month and billamt stand for the phone company identifier, the phone type the customer subscribes to, the month of subscription and the phone bill amount for that month. The rest of the attributes are for the company's name, their address and the number of phone products they provide to customers Assume that an update is to be made to this database to enter information about a new PhoneCompany not yet in the database that an existing Customer has now switched to (replacing the customer's old PhoneCompany). Answer the following questions on what specific relations, attributes and operations (eg. insert, modify, delete) that need to be done for this update to be implemented in this database Provide your answers both in descriptive sentence and using the formal database operations of INSERT, MODIFY DELETE as used in Chapter 5 of book with specific attributes and relations when possible. An example formal insert of a customer record into the Customer table is INSERT into Customer, I/ for new Customer record And an example descriptive sentence is i). do an insert operation for a new customer record into the Customer table (a) Give the set of needed insert, modify or delete operations for this update. (b) What types of constraints (explain using attributes, eg SSN of relevant files) would you expect to check for this update to be done? (c) Which of these constraints are key, entity integrity, and referential integrity constraints and which are not? (d) Specify all the referential integrity (foreign key) constraints on this database. 5 marks 5 marks 5 marks 5 marks