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 corret answer C. The analyst has prefetch enabled on the browser in use.
Explanation:
The analyst has like an indicator which is prefetch enabled on the browser in use.
Answer:
def leap_year(y):
if y % 4 == 0:
return 1
else:
return 0
def number_of_days(m,y):
if m == 2:
return 28 + leap_year(y)
elif m == 1 or m == 3 or m == 5 or m == 7 or m == 8 or m ==10 or m == 12:
return 31
elif m == 4 or m == 6 or m == 9 or m == 11:
return 30
def days(m,d):
if m == 1:
return 0 + d
if m == 2:
return 31 + d
if m == 3:
return 59 + d
if m == 4:
return 90 + d
if m == 5:
return 120 + d
if m == 6:
return 151 + d
if m == 7:
return 181 + d
if m == 8:
return 212 + d
if m == 9:
return 243 + d
if m == 10:
return 273 + d
if m == 11:
return 304 + d
if m == 12:
return 334 + d
def days_left(d,m,y):
if days(m,d) <= 60:
return 365 - days(m,d) + leap_year(y)
else:
return 365 - days(m,d)
print("Please enter a date")
day=int(input("Day: "))
month=int(input("Month: "))
year=int(input("Year: "))
choice=int(input("Menu:\n1) Calculate the number of days in the given month.\n2) Calculate the number of days left in the given year.\n"))
if choice == 1:
print(number_of_days(month, year))
if choice == 2:
print(days_left(day,month,year))
Explanation:
Hoped this helped
Answer:
umm let me check if my answer is right
Explanation:
Answer and Explanation:
Messages flow across an SDN controller's:
Northbound APIs:
• Messages which help in read/write state of the network and developing flow tables within the
state management layer.
• Notifications for the state-change events.
• The interaction between the controller and network control applications is done through the
northbound interface.
• Network control applications send messages to the controller.
Southbound APIs:
• Messages which help for the up-to-date view of the network's state like message for the
attached link has gone up or down, new devices are joined the network, or indications of the
device is up or down.
• Controller's southbound interface is the communication among the controller and the controlled
devices. Controlled devices are the recipients of the messages sent form the controller.
