Answer:
A primary key is a special relational database table column (or combination of columns) designated to uniquely identify each table record. A primary key is used as a unique identifier to quickly parse data within the table. A table cannot have more than one primary key.
Primary Key.
Candidate Key.
Alternate Key.
Super Key.
Composite Key.
Foreign Key.
Unique Key.
In the relational model of databases, a primary key is a specific choice of a minimal set of attributes that uniquely specify a tuple in a relation. Informally, a primary key is "which attributes identify a record," and in simple cases constitute a single attribute: a unique ID.
Explanation:
The missing word here is social.
Social engineering involves using simple human methods to steal data, such as looking through peoples’ drawers for pieces of paper on which they might have written down passwords, or perhaps sneaking a look at the keys you press while walking past your desk as you are typing your password. Such behaviors designed to steal your personal information are methods of social engineering.
Let me know if you have any questions.
Answer:
def newton(n):
#Define the variables.
t = 0.000001
esti = 1.0
#Calculate the square root
#using newton method.
while True:
esti = (esti + n / esti) / 2
dif = abs(n - esti ** 2)
if dif <= t:
break
#Return the result.
return esti
#Define the main function.
def main():
#Continue until user press enters.
while True:
try:
#Prompt the user for input.
n = int(input("Enter a number (Press Enter to stop):"))
#display the results.
print("newton = %0.15f" % newton(n))
except:
return
#Call the main function.
main()
Answer:
The delimiter use is "::".
Explanation:
The Java inbuilt String.split( ) function is use to split a String into an array of String.
The split( ) takes delimiter as arguments/parameter which determines at which point the string is to be broken down into different part/token.
From the above code snippet;
Each line in the file a.txt that is not null is splitted using the statement below:
String[ ] v = line.split("::");
The line is splitted using "::" as delimiter and the resulting array is then assigned to the variable 'v'.
For instance, a line in the file could take the form:
John::Smith::Music
When it is splitted,
String lname = John;
because lname make reference to index 0 of the array.
String fname = Smith;
because fname make reference to index 1 of the array.
String dept = Music;
and dept make reference to index 2 of the array.
