The nobel table can be used to practice more SUM and COUNT functions.

This tutorial concerns aggregate functions such as COUNT, SUM and AVG.

Exercises

Show the total number of prizes awarded.

SELECT COUNT(winner) FROM nobel

SELECT COUNT(winner) FROM nobel

List each subject - just once

SELECT DISTINCT subject FROM nobel

Show the total number of prizes awarded for Physics.

nobel(yr, subject, winner)

SELECT COUNT(subject) FROM nobel
  WHERE subject='Physics'

For each subject show the subject and the number of prizes.

nobel(yr,subject, winner)

SELECT subject, COUNT(winner)
  FROM nobel
 GROUP BY subject

For each subject show the first year that the prize was awarded.

nobel(yr, subject, winner)

SELECT subject, MIN(yr)
  FROM nobel
 GROUP BY subject

For each subject show the number of prizes awarded in the year 2000.

nobel(yr, subject, winner)

SELECT subject,COUNT(yr)
FROM nobel
WHERE yr=2000
GROUP BY subject

Show the number of different winners for each subject.

nobel(yr, subject, winner)

SELECT subject,COUNT(DISTINCT winner)
FROM nobel
GROUP BY subject

For each subject show how many years have had prizes awarded.

nobel(yr, subject, winner)

SELECT subject,COUNT(DISTINCT yr)
FROM nobel
GROUP BY subject

Using HAVING.

Show the years in which three prizes were given for Physics.

nobel(yr, subject, winner)

SELECT yr
FROM nobel
WHERE subject='Physics'
GROUP BY yr
HAVING COUNT(winner)=3

Show winners who have won more than once.

nobel(yr, subject, winner)

SELECT winner
FROM nobel
GROUP BY winner
HAVING COUNT(yr) > 1

Show winners who have won more than one subject.

nobel(yr, subject, winner)

SELECT winner
FROM nobel
GROUP BY winner
HAVING COUNT(DISTINCT subject)>1

<p>GROUP BY yr, subject

Show the year and subject where 3 prizes were given. Show only years 2000 onwards.

nobel(yr, subject, winner)

SELECT yr,subject
FROM nobel
WHERE yr>=2000
GROUP BY yr,subject
HAVING COUNT(winner)=3