exercises.sql

#01
Problem
Selecting Multiple Columns


When buying food, it is important to make sure it is fresh and not expired.
You are given the following 'Products' list:contentImageWrite a query to select the ProductName, ProductionDate and ExpirationDate.
Use the SELECT statement and separate the required columns by commas.

-- Solution 

SELECT ProductName, productionDate, ExpirationDate FROM products;

#02
Problem
The DISTINCT Keyword


At the conclusion of a bank transaction, 6 checks are printed -- 3 originals for the bank, and 3 copies for the customer.
Here is the list of all the checks named Operation

Write a query to show only the unique checks that are given to the customer.
Use the DISTINCT statement to return the unique values of mentioned column.

-- SOLUTION

/* table name: Operation */
SELECT DISTINCT checks FROM Operation;

#03
Sorting Results


Six players have competed in a chess tournament and their scores have been tallied.
Here is the table of Players:

Sort the players by losses to derive the leaderboard.
Recall the ORDER BY keyword.

-- Solution
?

#04
Problem
Logical Operators


You are given the following films table with details about superhero movies:

Write a query to output the names of all of the films which were produced by Marvel Studios in 2010 or later, sorted by the 'name' column.
Use the AND operator to combine two or more conditions.

-- SOLUTION
SELECT name FROM films WHERE production = 'Marvel Studios' and year >= 2010 ORDER BY name;

#05

Problem
The IN Operator


You are sorting football teams by leagues and given the following table named teams.

Write a query to output the team names and the countries of all teams that have played in La Liga (Spain), Premier League (England) and Bundesliga (Germany)․
Use the IN operator.

-- SOLUTION

SELECT teamname, country FROM teams WHERE country IN('Spain', 'England', 'Germany');


#06
Apartments
You want to rent an apartment and have the following table named Apartments:
Write a query to output the apartments whose prices are greater than the average and are also not rented, sorted by the 'Price' column.
Recall the AVG keyword.

--- SOLUTION
SELECT * FROM Apartments WHERE price > (SELECT AVG(price) FROM apartments) ORDER BY price;

#07


#08

#09
AVG

You are given the following table sam_grades, which shows Sam’s exam scores.contentImageWrite a query to output the average of Sam's exam scores for the first semester.
Use the AVG() function!

"""SOLUTION"""

SELECT AVG(score) FROM sam_grades WHERE semester = 1;

#10

#11
Problem
Joining Tables


You are given the following students and teachers tables
students (with their teachers ID's):contentImageteachers:contentImageWrite a query to output all of the students with their teachers' last names in one table, sorted by students ID.
The column with teachers' last names should be named "teacher" -- recall the AS keyword.

---solution
SELECT students.id, students.firstname, students.lastName, teachers.lastname 
As teacher
FROM students, teachers
WHERE  students.teacherID=Teachers.ID
ORDER BY students.ID;        
          
#12
Problem
INNER JOIN

You are working at a supermarket and you need to arrange products by categories. You are given the following tables:

products:contentImagecategories:contentImageEach product has a category.
Write a query to output all products with their categories (productname-price-categoryname) in one table.
Don't forget about the ON keyword while using INNER JOIN.

--- SOLUTION 

SELECT products.productname, products.price,
categories.categoryname

FROM products INNER JOIN categories

ON products.categoryid = categories.id

#13
Problem
UNION

FIDE wants to hold a major chess tournament and has decided to include players from the Norway Chess and Tata Steel tournaments.
Table NorwayChesscontentImageTable TataSteelcontentImage
Write a query to merge 'NorwayChess' and 'TataSteel' tables. Then order the merged table by 'Rating' in descending order and show the final table of participants.
Remember, you need to get a table without duplicates.

--- SOLUTION

SELECT player, country, birthyear, rating FROM 
norwaychess
UNION
SELECT player, country, birthyear, rating FROM
tatasteel ORDER BY rating DESC;

#14
Problem
The INSERT Statement


You have started a car rental service and have the following cars:

#GaragecontentImage

You plan to add two more vehicles to your garage:
6, 'Mercedes-Benz', 'G 63', 2020
7, 'Porsche', 'Panamera', 2020

Write a query to insert the new cars into your table named 'Garage'. Then show the table with the added records.

Use the INSERT statement to perform the operation.

""" SOLUTION """

INSERT INTO Garage (id, make, model, prodyear) 
VALUES (6,  'Mercedes-Benz',   'G 63',   2020), 
(7,   'Porsche',    'Panamera',     2020); 
SELECT * FROM Garage

#15
Problem
Deleting Data


You are manager in the supermarket.
Here is the products table showing a field for each item, along with the ExpireDate with the count of days remaining before item expiration.contentImageYou need to get rid of all the expired products.
Delete from the ‘products’ table all of the items whose 'ExpireDate' is less than 1 and show the table without any expired items.
The DELETE statement removes the data from the table permanently.

""" SOLUTION """
DELETE FROM products WHERE expiredate=0; 
SELECT * FROM products

#16
Creating a Table


You need to make a leaderboard for a video game.
It should have the following columns:
- place (INT)
- nickname (VARCHAR)
- rating (INT)

Write a query to create this table and insert the following top 3 players:
1, Predator, 9500
2, JohnWar, 9300
3, NightWarrior, 8900

Finally, show the resulting table.
Recall the INSERT statement to add the required data to the table.

--SOLUTION
CREATE TABLE leaderboard (
Place int,
Nickname VARCHAR(100),
Rating int);

INSERT INTO leaderboard (Place, Nickname,
Rating)
VALUES
( 1,'Predator',9500),
( 2,'Johnwar' ,9300),
( 3,'Nightwarrior',8900);

SELECT * FROM Leaderboard




#17

#18

#19

#20

#21
Zoo
You manage a zoo. Each animal in the zoo comes from a different country. Here are the tables you have:
AnimalscontentImageCountriescontentImage1) A new animal has come in, with the following details:
name - "Slim", type - "Giraffe", country_id - 1
Add him to the Animals table.
2) You want to make a complete list of the animals for the zoo’s visitors. Write a query to output a new table with each animal's name, type and country fields, sorted by countries.
Recall INSERT and INNER JOIN keywords.

-- SOLUTION -- 

/* name - "Slim", type - "Giraffe", country_id - 1 */

insert into animals values
('Slim','Giraffe',1);

SELECT initcap(a.name) as name, initcap(a.type) as type,
CASE
when a.country_id=3 then initcap('India')
when a.country_id=2 then initcap('Russia')
when a.country_id=1 then upper('USA')
END 
AS country
FROM Animals AS a inner join Countries AS c
on a.country_id=c.id
order by c.country Asc;