Solution for SUM and COUNT with nobel table

sum-and-count-nobel.sql

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+/*
+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(*) FROM nobel WHERE subject='Physics'
+
+--#4
+/*
+For each subject show the subject and the number of prizes. 
+*/
+SELECT subject, COUNT(*)
+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(winner)
+FROM nobel
+WHERE yr=2000
+GROUP BY subject
+
+--#7
+/*
+Show the number of different winners for each subject. 
+*/
+SELECT DISTINCT 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(yr)=3
+
+--#10
+/*
+Show winners who have won more than once. 
+*/
+SELECT winner FROM nobel
+GROUP BY winner
+HAVING COUNT(winner)>1
+
+--#11
+/*
+Show winners who have won more than one subject. 
+*/
+SELECT winner FROM nobel
+GROUP BY winner
+HAVING COUNT(DISTINCT subject) > 1
+
+--#12
+/*
+Show the year and subject where 3 prizes were given. Show only years 2000 onwards. 
+*/
+SELECT yr, subject FROM nobel
+WHERE yr >= 2000
+GROUP BY yr, subject
+HAVING COUNT(DISTINCT winner)=3