Which field is the major sort key? Which field is the minor sort key? What effect do these keys have on the order in which the rows are displayed?15.How do you join tables in access query? 16.When do you use an update query? 17.When do you use a delete query?
18.When do you use a make-table query?19.What is relational algebra?20.Describe the purpose of the SELECT command in relational algebra. 21.Describe the purpose of the PROJECT command in relational algebra.