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
Pay Day Lender
Explanation
A bank is a financial institution which is authorized by the government to accept deposits inform of cash or cheque from the public who are the customers, and it creates a credit. It saves money to for the customers and also provides security for the customers money. It also lends money to the customers as loan where they pay with interest within a given time. There are many types of banks which include credit unions, online banks,industrial, agricultural, retail banks and many others.
Answer:
DHCP is the dynamic host configuration protocol that enable the server for assigning the IP address to the computer. It is basically used to provide automatic IP addresses within the network. It is basically used to configure the default gateway and provide the DNS server data in the device.
The optional parameter when configuring DHCP are:
- Sub-net mask
- Router
- Domain server
- Broadcast address
- Host name
They are replaced by ExpressCard
Answer:
Explanation:
The basic concept of virtual reality is that they are a pair of lenses in a headset that allows you to visualize a virtual 3D world and become immersed within it. To do the exercises correctly Anna would need to follow the following basic steps.
Put the virtual glasses over her eyes, complete the exercises in the virtual world, take the virtual glasses off
The headset/glasses need to fit comfortably on her eyes and around her head so that she can clearly see the image on the lenses and so that the headset/glasses do not fall off while she is completing her exercises. Once she is done with her exercises Anna can simply take off her virtual glasses and put them away.
