For Each Of The Views, Explain How Updates Would Be Performed (if The

1.	For Each Of The Views, Explain How Updates Would Be Performed (if They Should Be Allowed At All)?
Answer» To insert (account-number, name) into the view deer-park we insert the tuple (Deer Park, account-number, null) into the account relation and the tuple (name, account-number) into the depositor relation. Updates to the VIEWS no-debt and avg-bal present SERIOUS problems. If we insert into the no-debt view, the system must reject the insertion if the customer has a LOAN. The OVERHEAD of updating through this view is so high that most systems would disallow UPDATE. The avg-bal view cannot be updated since the result of an aggregate operation depends on several tuples, not just one. To insert (account-number, name) into the view deer-park we insert the tuple (Deer Park, account-number, null) into the account relation and the tuple (name, account-number) into the depositor relation. Updates to the views no-debt and avg-bal present serious problems. If we insert into the no-debt view, the system must reject the insertion if the customer has a loan. The overhead of updating through this view is so high that most systems would disallow update. The avg-bal view cannot be updated since the result of an aggregate operation depends on several tuples, not just one.

For Each Of The Views, Explain How Updates Would Be Performed (if They Should Be Allowed At All)?

Answer»

To insert (account-number, name) into the view deer-park we insert the tuple (Deer Park, account-number, null) into the account relation and the tuple (name, account-number) into the depositor relation.

Updates to the VIEWS no-debt and avg-bal present SERIOUS problems. If we insert into the no-debt view, the system must reject the insertion if the customer has a LOAN. The OVERHEAD of updating through this view is so high that most systems would disallow UPDATE. The avg-bal view cannot be updated since the result of an aggregate operation depends on several tuples, not just one.

Updates to the views no-debt and avg-bal present serious problems. If we insert into the no-debt view, the system must reject the insertion if the customer has a loan. The overhead of updating through this view is so high that most systems would disallow update. The avg-bal view cannot be updated since the result of an aggregate operation depends on several tuples, not just one.

For Each Of The Views, Explain How Updates Would Be Performed (if They Should Be Allowed At All)?

Discussion

No Comment Found

Related InterviewSolutions

Reply to Comment