Solution 1:

QUERY 1
Display a list of customers and the total amount of their purchases, sorted by amount.

Sol)
SELECT CONCAT(CUSTOMER.Lname,' ', CUSTOMER.Fname) AS
CUSTOMER, Sum(`Order`.Price+`Order`.Tax) AS `Total Amount Of
Their Purchases`
FROM CUSTOMER INNER JOIN `ORDER` ON CUSTOMER.Customerid
= `ORDER`.Customerid
GROUP BY CUSTOMER.Customerid
ORDER BY Sum(`Order`.Price+`Order`.Tax) DESC;

QUERY 2
Display the name of the Item, the total number of each item sold and the total sales (purchase price times quantity) for each item.  Column headings are Name, Total sold, and Total sales.

Sol)
SELECT PRODUCT.name AS Name, Sum(ITEM.Quantity) AS `Total
sold`, PRODUCT.cost*Sum(ITEM.Quantity) AS `Total sales`
FROM PRODUCT INNER JOIN ITEM ON PRODUCT.productid =
ITEM.Type
GROUP BY ITEM.Type;

QUERY 3
Display the names of the Widgets that have sold more than 1 item .  Your answer should display a name only once.  Use a HAVING clause.

Sol)
SELECT DISTINCT PRODUCT.name
FROM PRODUCT INNER JOIN ITEM ON PRODUCT.productid =
ITEM.Type
GROUP BY PRODUCT.productid
HAVING (((Count(ITEM.Type))>1));

QUERY 4
Display the Customer name, the order number, the product name, the quantity of the product, and the price of the product in order number order where the total cost of the order is greater than $500.00.

Sol)
SELECT CONCAT(CUSTOMER.Lname,' ', CUSTOMER.Fname) AS
Customer, `ORDER`.Ordernr, PRODUCT.name, ITEM.Quantity,
PRODUCT.cost
FROM PRODUCT INNER JOIN ((CUSTOMER INNER JOIN `ORDER`
ON CUSTOMER.Customerid = `ORDER`.Customerid) INNER JOIN
ITEM ON `ORDER`.Ordernr = ITEM.Ordernr) ON
PRODUCT.productid = ITEM.Type
WHERE (((`ORDER`.Price+`ORDER`.Tax)>500))
ORDER BY `ORDER`.Ordernr;
QUERY 5
Dislpay a list of customers and salesperson who sold them something and the date of the sale.

Sol)
SELECT CONCAT(CUSTOMER.lname,' ', CUSTOMER.fname) AS
Customer, CONCAT(EMPLOYEE.lname,' ', EMPLOYEE.fname) AS
Salesperson, `ORDER`.`Date purchased` AS `Date of sale`
FROM (`ORDER` INNER JOIN EMPLOYEE ON
EMPLOYEE.employeeid=`ORDER`.salesperson) INNER JOIN
CUSTOMER ON CUSTOMER.Customerid=`ORDER`.customerid;

Solution 2:
Q1) I want a list of countries and languages spoken there that are used by more than 50% of the population.
Sol:
SELECT COUNTRY.Name, `COUNTRY LANGUAGE`.Language
FROM COUNTRY INNER JOIN `COUNTRY LANGUAGE` ON COUNTRY.Code = `COUNTRY LANGUAGE`.Countrycode
WHERE (((`COUNTRY LANGUAGE`.Percentage)>50));

Q2) I want a list of countries and the number of languages spoken there for all countries with 10 or more languages.
Sol:
SELECT COUNTRY.Name, Count(`COUNTRY LANGUAGE`.Language) AS CountOfLanguage
FROM COUNTRY INNER JOIN `COUNTRY LANGUAGE` ON COUNTRY.Code = `COUNTRY LANGUAGE`.Countrycode
GROUP BY COUNTRY.Name
HAVING (((Count(`COUNTRY LANGUAGE`.Language))>=10));

Q3) I want a list of countries and official languages and precentages where the official language is spoken by less then 50% of the population.
Sol:
SELECT COUNTRY.Name, `COUNTRY LANGUAGE`.Language, `COUNTRY LANGUAGE`.Percentage
FROM COUNTRY INNER JOIN `COUNTRY LANGUAGE` ON COUNTRY.Code = `COUNTRY LANGUAGE`.Countrycode
WHERE (((`COUNTRY LANGUAGE`.Percentage)<50) AND ((`COUNTRY LANGUAGE`.Isofficial)=True));

Q4) I want a list of countries and cities where the city population is greater than 10% of the country population.
Sol:
SELECT COUNTRY.Name, CITY.Name
FROM COUNTRY INNER JOIN CITY ON COUNTRY.Code = CITY.`Country code`
WHERE (((CITY.Population)>0.1*COUNTRY.Population));

Q5) I want a list of all African countries that gained their independence since 1964.
Sol:
SELECT COUNTRY.Name
FROM COUNTRY
WHERE (((COUNTRY.Continent)="Africa") AND ((COUNTRY.Indepyear)>"1964"));

Q6) I want the name of the country, the name of the district, and the number of cities in each district for each district that has 10 or more cities in it.
Sol:
SELECT COUNTRY.Name, CITY.District, Count(CITY.ID) AS CityCount
FROM COUNTRY INNER JOIN CITY ON COUNTRY.Code = CITY.`Country code`
GROUP BY COUNTRY.Name, CITY.District
HAVING (((Count(CITY.ID))>=10));

Q7) I want the average life expectancy for each continent, from highest to lowest.
Sol:
SELECT COUNTRY.Continent, Avg(COUNTRY.Lifeexpectancy) AS AvgOfLifeexpectancy
FROM COUNTRY
GROUP BY COUNTRY.Continent
ORDER BY Avg(COUNTRY.Lifeexpectancy) DESC;

Q8) I want the name of the country and the life expectancy for each country that has a life expectancy less than the average life expectancy.
Sol:
SELECT COUNTRY.Name, COUNTRY.Lifeexpectancy
FROM COUNTRY WHERE COUNTRY.Lifeexpectancy<(SELECT AVG(COUNTRY.Lifeexpectancy) from COUNTRY);

Q9) I want a list of languages spoken in the United States and the number of people in the United States who speak that language.
Sol:
SELECT `COUNTRY LANGUAGE`.Language, 0.01*Percentage*Population AS NumberOfPeople
FROM COUNTRY INNER JOIN `COUNTRY LANGUAGE` ON COUNTRY.Code = `COUNTRY LANGUAGE`.Countrycode
WHERE (((COUNTRY.Name)="United States"));

Q10) I want the name of the country and its population for every country that has more than the average population of the world sorted by population.
Sol:
SELECT COUNTRY.Name, COUNTRY.Population
FROM COUNTRY
WHERE (((COUNTRY.Population)>(SELECT AVG(COUNTRY.Population) FROM COUNTRY)))
ORDER BY COUNTRY.Population DESC;