Database System Concepts
7th Edition
ISBN: 9781260084504
Author: Abraham Silberschatz, S. Sudarshan, Abraham, Henry Korth, Silberschatz Abraham, Silberschatz Professor
Publisher: McGraw-Hill Education
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Expert Solution & Answer
Chapter 25, Problem 3PE
Explanation of Solution
a.
Example for a given situation:
- The relation “r” is clustered by the attribute a in below case.
- Consider that the relation “r” is not clustered on the attribute “a”...
Explanation of Solution
b.
Justification:
- It is possible only when there is a mutual relationship between “a” and “b” attribute.
- The a-value attribute with tuples “t1” is less than the a-value attribute with tuples “t22&#x...
Explanation of Solution
c.
Suggestion:
- For both the queries the physical order of the tuples cannot be suited.
- To execute the query efficiently, “r” is clustered on 'a' and we have B+ tree index on “b”...
Expert Solution & Answer
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Students have asked these similar questions
5. Word FrequencyWrite a program that reads the contents of a text file. The program should create a dictio-nary in which the keys are the individual words found in the file and the values are the number of times each word appears. For example, if the word “the” appears 128 times, the dictionary would contain an element with 'the' as the key and 128 as the value. The program should either display the frequency of each word or create a second file containing a list of each word and its frequency.
3.) File Encryption and DecryptionWrite a program that uses a dictionary to assign “codes” to each letter of the alphabet. For example:
codes = { ‘A’ : ‘%’, ‘a’ : ‘9’, ‘B’ : ‘@’, ‘b’ : ‘#’, etc . . .}Using this example, the letter A would be assigned the symbol %, the letter a would be assigned the number 9, the letter B would be assigned the symbol @, and so forth.
The program should open a specified text file, read its contents, then use the dictionary to write an encrypted version of the file’s contents to a second file. Each character in the second file should contain the code for the corresponding character in the first file.
Write a second program that opens an encrypted file and displays its decrypted contents on the screen.
Returns an US standard formatted phone number, in the format of
(xxx) xxx-xxxx
the AreaCode, Prefix and number being each part in order.
Testing Hint: We be exact on the format of the number when
testing this method. Make sure you think about how to convert
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