a. What will be the field size for the ProductLineName field in the Product table? Why? b. In Figure 1-19, how is the ProductID field in the Prod. uct table specified to be required? Why is it a required attribute? c. In Figure 1-19, explain the function of the FOREIGN KEY definition d. In Figure 1-19, explain the purpose of the NOT NULL specification associated with ProductID. 1-47. Consider the SQL query in Figure 1-20 a. How is Sales to Date calculated? b. How would the query have to change if Helen Jarvis wanted to see the results for all of the product lines, not just the Home Office product line? c. The part of the query starting with WHERE (the so called WHERE clause) has two different types of conditionsthe last one is clearly different from the first three. Explain how. 1-48. Helen Jarvis wants to determine the most important cus- tomers for Home Office products. She requests a listing of year-to-date total dollar sales for each customer who bought these products, as revealed by invoiced payments. The list is to be sorted in descending order so that the larg- est customer heads the list. a. Look at Figure 1-16 and determine what entities are required to produce this list. b. Which entities will be involved in the SQL query that will give Helen the information she needs? 1-49 In this what is the underlying reason for this ambiguity? 1-46. Answer the following questions concerning Figures 1-18 and 1-19: 1. The Database Environment and Development Proc SELECT Product.Productio, Product.Product Description Product PACurrentYeurSalesGoal. FIGURE 1-20 SQL que Home Office sales to g comparison (Order Quantity ProductPrice) AS Sales ToDate FROM Order.OrderLine, Product ProductLine WHERE Order.Order Number = OrderLine Order Number AND Product ProductID = Ordered Product Products AND Product ProductID = ProductLine Products AND Product ProductLineName = 'Home Office; FIGURE 1-21 Home TOP Non Vearoa DECIMAL) IGURE 1-19 Produkte CREATE TABLE Product T hochou NUMBER(110) NOT NULL PRIMARY KEY Product Description VARCHAR (60) Product Pinish VARCHAR (20), Product Standard Price DECIMAL (6,2). Productcoot DECIMAL Product Prior YearGoal DECIMAL ProductCurrentYearGoal DECIMAL. ProductLineID VARCHAR (40), FOREIGN KEY (ProductLineID) REFERENCES ProductLine T (ProductLine