For the view of Exercise 4.18, explain why the database system would not allow a tuple to be inserted into the database through this view.
For reference
For the database of Figure 4.12, write a query to find the ID of each employee with no manager. Note that an employee may simply have no manager listed or may have a null manager. Write your query using an outer join and then write it again using no outer join at all.
OUTER JOIN
select e.ID from employee e left outer join manages m on e.ID = m.ID
where m.manager_id is null;
NO OUTER
select e.ID from employee e where e.ID not in (select m.ID from manages m) or e.ID in (select m.ID from manages m where m.manager_id is null);
The answer for this question is YES
The number of memory words used to store the string "rainbow" is 8.
Researches at symantec have uncovered a version of the stuxnet computer virus that was used to attack irans nuclear program in November.
Answer:A password or a PIN
Explanation: Develetech is a industry that has the a internet page and can also be used in the mobile devices. There is particular authorization that the organization provides to an individual user for accessing of the services to maintain the security .The security is maintained by providing the devices with an encrypted text that is known as the password. The user has to enter the pin or password to execute the service on device.
