SUM and COUNT Quiz

bbc table

Link

1. Select the statement that shows the sum of population of all countries in 'Europe'

   SELECT SUM(population) FROM bbc WHERE region = 'Europe'

2. Select the statement that shows the number of countries with population smaller than 150000

    SELECT COUNT(name) FROM bbc WHERE population < 150000

3. Select the list of core SQL aggregate functions AVG(), COUNT(), MAX(), MIN(), SUM()

4. Select the result that would be obtained from the following code:

    SELECT region, SUM(area)
      FROM bbc 
     WHERE SUM(area) > 15000000 
     GROUP BY region

   No result due to invalid use of the WHERE function

5. Select the statement that shows the average population of 'Poland', 'Germany' and 'Denmark'

    SELECT AVG(population) FROM bbc 
    WHERE name IN ('Poland', 'Germany', 'Denmark')

6. Select the statement that shows the medium population density of each region

    SELECT region, SUM(population)/SUM(area) AS density 
    FROM bbc 
    GROUP BY region

7. Select the statement that shows the name and population density of the country with the largest population

    SELECT name, population/area AS density 
    FROM bbc 
    WHERE population = (SELECT MAX(population) FROM bbc)

8. Pick the result that would be obtained from the following code:

    SELECT region, SUM(area) 
      FROM bbc 
     GROUP BY region 
     HAVING SUM(area)<= 20000000

Americas	732240
Middle East	13403102
South America	17740392
South Asia	9437710