(A) What Is a SQL*Plus Script? Why Is It a Good

Essay

(a) What is a SQL*Plus script? Why is it a good practice to create a log file while a SQL*Plus script is executed, and how can the log file be created? (b) What can a 'database trigger' be used for? Explain concisely what the code below does.
(c) Assume the following tables:
Order(orderNo, statusCode, customerNo,…)
Item(itemNo, orderNo, price, amount,…)
which capture, among others, the items that are ordered by customers. Explain what the following code is and explain how it works by writing comments against each line of the code:
FUNCTION total_sales (customerNo_in IN orders.customerNo%TYPE,
statusCode_in IN order.statusCode%TYPE:=NULL)