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QUESTION 2 40 MARKS
2.1 For the relations s and r in your study manual of our chapter 2 (i.e., joining two relations),
suppose we type a collection of relational algebra queries, and get the following results.
A B C D E
A 2 a 10 B
b 2 a 10 b
Please explain how this happened? If you think this result could happen in practice, please write the
corresponding relational algebra queries; otherwise, please explain why. (4

How many levels of abstraction a typical DB system should hold? What’s the purpose of each of these abstraction levels?

For the relations s and r in your study manual of our chapter 2 (i.e., joining two relations), suppose we type a collection of relational algebra queries, and get the following results. A B C D E A 2 a 10 B b 2 a 10 b Please explain how this happened? If you think this result could happen in practice, please write the corresponding relational algebra queries; otherwise, please explain why.

Define and discuss the concept of transitive dependency. Include an example. (

What is SQL, and is SQL a scripting language? What do you have to support your answer?

3. Find audio tracks which have a length longer than the average length of all
the audio tracks;
4. Which playlists do not contain any tracks for the artists “Black Sabbath" nor
“Chico Buarque"?

~~ Tracks is a table
~~ Playlist is a table

Name Region Area Population GDP
Afghanistan South Asia 652225 260000000
Albania Europe 28728 3200000 6656000000
Algeria Middle East 2400000 32900000 75012000000
Andorra Europe 468 64000
Bangladesh South Asia 143998 152600000 67144000000
United Kingdom Europe 242514 59600000 2022824000

Now based on the above table

a) Write a query that shows the name, region and population of the smallest country in each region.

b) Select the code that shows the countries with population smaller than Russia but bigger than Denmark

How many levels of abstraction a typical database should hold

I am trying to figure out the formula for this question. I tried but i can't figure it out:

create a calculated field with the column label Discount Price that subtracts the Price times the Current Discount from the Price.

How to excecute join queries in hibernate?