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:
The answer is "Need-To-Know Access Control Principle"
Explanation:
There are three types of access control methods such as Role-Based Access Control, Discretionary Access Control and Mandatory Access Control.
The access control principle that limits/blocks the user from gaining access to a folder/information/procedure within the system is called "Need-To-Know Access Control Principle".
I hope this answer helps.
Answer:
NAS systems are networked appliances that contain one or more storage drives, often arranged into logical, redundant storage containers or RAID.
Answer:
this would be .128 terabytes
Explanation:
This would be since for a whole terabyte you need 1000 gigabytes every 1000 gigabytes is a terabyte for example let’s say you have 5250 gigabytes you would have 5.250 terabytes that simple hope this helped!
Client/Server and Peer-to-Peer networks are the two major network architecture models in use today. They each have advantages and disadvantages that can be used to benefit a particular outcome.
Briefly, the client/server model relates to one or many client performing relatively simple requests, which are then executed by a server. The server is performing more complex tasks, and often interacting with many clients simultaneously. Examples of client/server models include most websites, including the Brainly page you are running right this instant. Your web browser is acting as a client, and the Brainly.com website is running as a web server. It receives simple requests or information from your browser, such as clicking on a question or text typed by your keyboard, and then acts on this information by consulting a database, returning values, or returning a whole new web page to your browser. The client/server model is very powerful in business as it allows powerful and secure server-side processing and relatively simple clients. Office 365 that runs all microsoft office suites such as word and excel in a web browser on 'the cloud' is an example of a highly sophisticated client/server architecture.
By contrast, peer-to-peer networks are a distributed architecture of equals. Instead of a simple client and complex server, all clients are equals and link together to form nodes on a distributed network. There is no central control (server) and each node acts as a client and server to other nodes. This is also an extremely powerful network; as there is no central control it is difficult to shut down a peer-to-peer network. Taking out one node will not break the network in comparison to the client/server architecture where if the server goes down, services halt. Prime examples of famous peer-to-peer networks are the Bitcoin network and similar cryptographic currency networks, and music and file sharing networks such as Torrents. The torrent tracker websites are client/server however once a torrent is loaded into a torrent downloading application, the file is collectively downloaded from hundreds of 'peers' across the world as part of the torrent peer-to-peer network.
