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);
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<span>Filter installation in
ADSL setup, the DSL filters should on connections leading to an analog phone.
The DSL modem and phone were share on the same jack. ADSL is a type of digital
subscriber line machinery, a data communication that enables faster data transfer
over copper telephone lines.</span>
Answer:
Symmetric encryption or single key encryption
Answer:
sendObject(John_Doe)
Explanation:
To invoke a method, simply call the name of the method, followed by it's arguments in parenthesis. i.e methodname(argument).
In this case, the name of the method is sendObject and it's argument is a Customer object stored in or referenced by a variable John_Doe.
The above is true since the method is defined in the same class that calls it. Otherwise, it is not valid.
