Answer:
this is the method of processing wood
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:
Artificial Intelligence.
Automated personal digital assistant.
THz frequencies for Communications (5G & 6G)
Blockchain.
Virtual reality and augmented reality.
Internet of Things (IoT)
Visible light communication.
LTE.
Explanation:
The first one and last one
Answer:
Explanation:
When most non-technical people hear the term “seven layers”, they either think of the popular Super Bowl bean dip or they mistakenly think about the seven layers of Hell, courtesy of Dante’s Inferno (there are nine). For IT professionals, the seven layers refer to the Open Systems Interconnection (OSI) model, a conceptual framework that describes the functions of a networking or telecommunication system.
The model uses layers to help give a visual description of what is going on with a particular networking system. This can help network managers narrow down problems (Is it a physical issue or something with the application?), as well as computer programmers (when developing an application, which other layers does it need to work with?). Tech vendors selling new products will often refer to the OSI model to help customers understand which layer their products work with or whether it works “across the stack”.
Layer 7 - Application
To further our bean dip analogy, the Application Layer is the one at the top--it’s what most users see. In the OSI model, this is the layer that is the “closest to the end user”. It receives information directly from users and displays incoming data it to the user. Oddly enough, applications themselves do not reside at the application layer. Instead the layer facilitates communication through lower layers in order to establish connections with applications at the other end. Web browsers (Google Chrome, Firefox, Safari, etc.) TelNet, and FTP, are examples of communications that rely on Layer 7.
Layer 6 - Presentation
The Presentation Layer represents the area that is independent of data representation at the application layer. In general, it represents the preparation or translation of application format to network format, or from network formatting to application format. In other words, the layer “presents” data for the application or the network. A good example of this is encryption and decryption of data for secure transmission - this happens at Layer 6.
