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);
Answer:
Both b and c
Explanation:
Dotted Decimal notation is a presentation of numerical data which is expressed as decimal numbers separated by full stops. Dotted decimal notation expresses each eight bit sections of 32 bit numbers as decimal value. It provides convenient notation which is easy to understand by the people who are IT experts.
True it usually shows up with a blue underline
Answer:
-ea
Explanation:
We can enable or disable assertions in java, by default this assertions are disabled at runtime, but we can use two commands, for example, if we want to enable assertions at various granularities, we can use the -enableassertions, or -ea, switch, if we want to disable at various granularities, is -disableassertions, or -da.
Answer:
From a hardware standpoint, the CPU is most likely the main component. From a software standpoint, macOS and Windows are complex software systems.
Explanation:
