SQL ZOO练习——The nobel table can be used to practice more SUM and COUNT functions

1. Show the total number of prizes awarded.

SELECT COUNT(winner) FROM nobel

2. List each subject - just once.

SELECT DISTINCT subject FROM nobel

3. Show the total number of prizes awarded for Physics.

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

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

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

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

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

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

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

7. Show the number of different winners for each subject.

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

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

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

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

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

10. Show winners who have won more than once.

SELECT winner FROM nobel
  GROUP BY winner
    HAVING COUNT(winner) >= 2