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);
I don't think so because the old computers may have not been to date as what we have now but check it out and see.
Answer:
True
Explanation:
When using databases in a project, not everyone has the same access level, e.g the database admin may have the highest level of access (access to data on live mode), the software testers have their own level of access (access to data on test mode) and so on.
