Exercise 5.5 Consider the instance of the Sailors relation shown in Figure 5.1. 1. Write SQL queries to compute the average rating, using AVG; the sum of the ratings, using SUM; and the number of...

No/ sql

Extracted text: Exercise 5.5 Consider the instance of the Sailors relation shown in Figure 5.1. 1. Write SQL queries to compute the average rating, using AVG; the sum of the ratings, using SUM; and the number of ratings, using COUNT. 2. If you divide the sum just computed by the count, would the result be the same as the average? How would your answer change if these steps were carried out with respect to the age field instead of rating? 3. Consider the following query: Find the names of sailors with a higher rating than all sailors with age < 21.="" the="" following="" two="" sql="" queries="" attempt="" to="" obtain="" the="" answer="" to="" this="" question.="" do="" they="" both="" compute="" the="" result?="" if="" not,="" explain="" why.="" under="" what="" conditions="" would="" they="" compute="" the="" same="" result?="" select="" s.sname="" from="" sailors="" s="" where="" not="" exists="" select="" from="" sailors="" s2="" where="" s2.age="">< 21="" and="" s.rating=""><= s2.rating="">