SQLZOO练习及答案

0.sqlzoo

https://sqlzoo.net/

1.select Basics

1.Modify it to show the population of Germany

SELECT population
FROM world
WHERE name ='Germany'

2.Show the name and the population for 'Sweden', 'Norway' and 'Denmark'.

SELECT name,population
FROM world
WHERE name in ('Sweden','Norway','Denmark')

3. Modify it to show the country and the area for countries with an area between 200,000 and 250,000.

SELECT name,area
FROM world
WHERE area BETWEEN 200000 AND 250000

2.SELECT from WORLD Tutorial

1.Read the notes about this table. Observe the result of running this SQL command to show the name, continent and population of all countries.

SELECT name,continent,population
FROM world

2.Show the name for the countries that have a population of at least 200 million. 200 million is 200000000, there are eight zeros

SELECT name
FROM world
WHERE population >200000000

3.Give the name and the per capita GDP for those countries with a population of at least 200 million.

SELECT name,gdp/population 
FROM world
WHERE population >200000000

4.Show the name and population in millions for the countries of the continent 'South America'. Divide the population by 1000000 to get population in millions.

SELECT name,population/1000000
FROM world
WHERE continent = 'South America'

5.Show the name and population for France, Germany, Italy

SELECT name,population
FROM world
WHERE name in ('France','Germany','Italy')

6.Show the countries which have a name that includes the word 'United'

SELECT name
FROM world
WHERE name LIKE 'United%'

7.Show the countries that are big by area or big by population. Show name, population and area.

Two ways to be big: A country is big if it has an area of more than 3 million sq km or it has a population of more than 250 million.

SELECT name,population,area
from world
WHERE area>3000000 OR population >250000000

8.Exclusive OR (XOR). Show the countries that are big by area (more than 3 million) or big by population (more than 250 million) but not both. Show name, population and area.

Australia has a big area but a small population, it should be included.
Indonesia has a big population but a small area, it should be included.
China has a big population and big area, it should be excluded.
United Kingdom has a small population and a small area, it should be excluded.

SELECT name,population,area
FROM world
WHERE (area > 3000000 AND population <=250000000)
OR (area<=3000000 AND population>250000000)

9.Show the name and population in millions and the GDP in billions for the countries of the continent 'South America'. Use the ROUND function to show the values to two decimal places.

For South America show population in millions and GDP in billions both to 2 decimal places.

SELECT name,ROUND(population/1000000,2),ROUND(gdp/1000000000,2)
FROM world
WHERE continent ='South America'

10.Show the name and per-capita GDP for those countries with a GDP of at least one trillion (1000000000000; that is 12 zeros). Round this value to the nearest 1000.

Show per-capita GDP for the trillion dollar countries to the nearest $1000.

SELECT name,ROUND(gdp/population,-3)
FROM world
WHERE gdp>1000000000000

11.Greece has capital Athens.

Each of the strings 'Greece', and 'Athens' has 6 characters.

Show the name and capital where the name and the capital have the same number of characters.

You can use the LENGTH function to find the number of characters in a string

SELECT name,capital
from world
WHERE LENGTH(name)=LENGTH(capital)

12.The capital of Sweden is Stockholm. Both words start with the letter 'S'.

Show the name and the capital where the first letters of each match. Don't include countries where the name and the capital are the same word.
You can use the function LEFT to isolate the first character.
You can use <> as the NOT EQUALS operator.

SELECT name,capital
FROM world
WHERE LEFT(name,1)=LEFT(capital,1)
AND name <> capital

13.Equatorial Guinea and Dominican Republic have all of the vowels (a e i o u) in the name. They don't count because they have more than one word in the name.

Find the country that has all the vowels and no spaces in its name.

You can use the phrase name NOT LIKE '%a%' to exclude characters from your results.
The query shown misses countries like Bahamas and Belarus because they contain at least one 'a'

SELECT name
   FROM world
WHERE name LIKE '%a%'
AND name LIKE '%e%'
AND name LIKE '%i%'
AND name LIKE '%o%'
AND name LIKE '%u%'
AND name NOT LIKE '% %'

3.select fromNobel

1.Change the query shown so that it displays Nobel prizes for 1950.

SELECT *
FROM nobel
WHERE yr=1950

2.Show who won the 1962 prize for Literature.

SELECT winner
FROM nobel
WHERE yr=1962
AND subject='Literature'

3.Show the year and subject that won 'Albert Einstein' his prize.

SELECT yr,subject
FROM nobel
WHERE winner ='Albert Einstein'

4.Give the name of the 'Peace' winners since the year 2000, including 2000.

SELECT winner
FROM nobel
WHERE subject ='Peace'
AND yr >=2000

5.Show all details (yr, subject, winner) of the Literature prize winners for 1980 to 1989 inclusive.

SELECT *
FROM nobel
WHERE subject='Literature'
AND yr>=1980
AND yr<=1989

6.Show all details of the presidential winners:

Theodore Roosevelt
Woodrow Wilson
Jimmy Carter
Barack Obama

SELECT * 
FROM nobel
WHERE winner in ('Theodore Roosevelt','Woodrow Wilson','Jimmy Carter','Barack Obama')

7.Show the winners with first name John

SELECT winner
FROM nobel
WHERE winner LIKE "John%"

8.Show the year, subject, and name of Physics winners for 1980 together with the Chemistry winners for 1984.

SELECT *
FROM nobel
WHERE 
(subject='Physics' AND yr='1980')
OR
(subject='Chemistry' AND yr='1984')

9.Show the year, subject, and name of winners for 1980 excluding Chemistry and Medicine

SELECT *
FROM nobel
WHERE yr=1980
AND subject<>'Chemistry'
AND subject<>'Medicine'

10.Show year, subject, and name of people who won a 'Medicine' prize in an early year (before 1910, not including 1910) together with winners of a 'Literature' prize in a later year (after 2004, including 2004)

SELECT *
FROM nobel
WHERE 
(subject='Medicine' AND yr<1910)
OR
(subject='Literature' AND yr>=2004)

11.Find all details of the prize won by PETER GRÜNBERG

这道题没搞懂，如何处理非utf8字符？？

SELECT *
FROM nobel
WHERE winner='PETER GRÜNBERG'

12.Find all details of the prize won by EUGENE O'NEILL

单引号转义

SELECT *
FROM nobel
WHERE winner = 'EUGENE O\'NEILL'

SELECT *
FROM nobel
WHERE winner = "EUGENE O'NEILL"

13.List the winners, year and subject where the winner starts with Sir. Show the the most recent first, then by name order.

SELECT winner,yr,subject
FROM nobel
WHERE winner LIKE "Sir%"
ORDER BY yr DESC,winner ASC

14.The expression subject IN ('Chemistry','Physics') can be used as a value - it will be 0 or 1.好题

Show the 1984 winners and subject ordered by subject and winner name; but list Chemistry and Physics last.

SELECT winner, subject
  FROM nobel
 WHERE yr=1984
 ORDER BY  subject IN ('Physics','Chemistry'),subject,winner

4.select within select

1.List each country name where the population is larger than that of 'Russia'.

SELECT name
FROM world
WHERE population >
(SELECT population
FROM world
WHERE name='Russia')

2.Show the countries in Europe with a per capita GDP greater than 'United Kingdom'.

SELECT name
FROM world w1
WHERE continent ='Europe'
AND gdp/population>
(SELECT gdp/population
FROM world
WHERE name='United Kingdom'
)

3.List the name and continent of countries in the continents containing either Argentina or Australia. Order by name of the country.

SELECT name,continent
FROM world
WHERE continent IN 
(SELECT DISTINCT(continent)
FROM world
WHERE name = 'Argentina'
OR name='Australia'
)
ORDER BY name

4.Which country has a population that is more than Canada but less than Poland? Show the name and the population.

SELECT name,population
FROM world
WHERE population>
(SELECT population FROM world WHERE name='Canada')
AND population<
(SELECT population FROM world WHERE name='Poland')

5.Germany (population 80 million) has the largest population of the countries in Europe. Austria (population 8.5 million) has 11% of the population of Germany.

Show the name and the population of each country in Europe. Show the population as a percentage of the population of Germany.

SELECT name,CONCAT(ROUND(population*100/(SELECT population FROM world WHERE name='Germany'),0),'%')
FROM world
WHERE continent ='Europe'

6.Which countries have a GDP greater than every country in Europe? [Give the name only.] (Some countries may have NULL gdp values)

SELECT name
FROM world
WHERE gdp>ALL(
SELECT gdp
FROM world
WHERE continent='Europe'AND gdp!='null')

7.Find the largest country (by area) in each continent, show the continent, the name and the area:

SELECT continent,name,area
FROM world w1
WHERE w1.area>=ALL(
SELECT w2.area
FROM world w2
WHERE w2.continent = w1.continent)

8.List each continent and the name of the country that comes first alphabetically.

SELECT w1.continent,w1.name
FROM world w1
WHERE w1.name=(
SELECT w2.name
FROM world w2
WHERE w2.continent= w1.continent
ORDER BY w2.name
LIMIT 0,1)

9.Find the continents where all countries have a population <= 25000000. Then find the names of the countries associated with these continents. Show name, continent and population.

SELECT name,continent,population
FROM world
WHERE continent NOT IN(
SELECT DISTINCT(continent)
FROM world
WHERE population>25000000)

10.Some countries have populations more than three times that of any of their neighbours (in the same continent). Give the countries and continents.好题！

注意这个any的含义

SELECT w1.name,w1.continent
FROM world w1
WHERE w1.population/3 >=
ALL(
SELECT w2.population
FROM world w2
WHERE  w2.continent=w1.continent
AND w1.name!=w2.name)

5.sum and count

1.Show the total population of the world.

SELECT SUM(population)
FROM world

2.List all the continents - just once each.

SELECT DISTINCT(continent)
FROM world

3.Give the total GDP of Africa

SELECT SUM(gdp)
FROM world
WHERE continent='Africa'

4.How many countries have an area of at least 1000000

SELECT COUNT(name)
FROM world
WHERE area>=1000000

5.What is the total population of ('Estonia', 'Latvia', 'Lithuania')

SELECT SUM(population)
FROM world
WHERE name in ('Estonia','Latvia','Lithuania')

6.For each continent show the continent and number of countries. GROUPBY HAVING

SELECT continent,COUNT(name)
FROM world 
GROUP BY continent

7.For each continent show the continent and number of countries with populations of at least 10 million.

SELECT continent,COUNT(name)
FROM world
WHERE population>=10000000
GROUP BY continent

8.List the continents that have a total population of at least 100 million.

SELECT continent
FROM world
GROUP BY continent
HAVING SUM(population)>=100000000

6.join

1.The first example shows the goal scored by a player with the last name 'Bender'. The * says to list all the columns in the table - a shorter way of saying matchid, teamid, player, gtime

Modify it to show the matchid and player name for all goals scored by Germany. To identify German players, check for: teamid = 'GER'

SELECT matchid,player
FROM goal
WHERE teamid='GER'

2.From the previous query you can see that Lars Bender's scored a goal in game 1012. Now we want to know what teams were playing in that match.

Notice in the that the column matchid in the goal table corresponds to the id column in the game table. We can look up information about game 1012 by finding that row in the game table.

Show id, stadium, team1, team2 for just game 1012

SELECT id,stadium,team1,team2
FROM game
WHERE id=1012

3.You can combine the two steps into a single query with a JOIN.

SELECT *
FROM game JOIN goal ON (id=matchid)
The FROM clause says to merge data from the goal table with that from the game table. The ON says how to figure out which rows in game go with which rows in goal - the matchid from goal must match id from game. (If we wanted to be more clear/specific we could say
ON (game.id=goal.matchid)

The code below shows the player (from the goal) and stadium name (from the game table) for every goal scored.

Modify it to show the player, teamid, stadium and mdate for every German goal.

SELECT player,teamid,stadium,mdate
FROM game
JOIN goal ON(id=matchid)
WHERE teamid='GER'

4.Show the team1, team2 and player for every goal scored by a player called Mario player LIKE 'Mario%'

SELECT team1,team2,player
FROM game
JOIN goal ON(id=matchid)
WHERE player LIKE 'Mario%'

5.Show player, teamid, coach, gtime for all goals scored in the first 10 minutes gtime<=10

SELECT player,teamid,coach,gtime
FROM goal 
JOIN eteam ON teamid = id
WHERE gtime <=10

6.To JOIN game with eteam you could use either

game JOIN eteam ON (team1=eteam.id) or game JOIN eteam ON (team2=eteam.id)

Notice that because id is a column name in both game and eteam you must specify eteam.id instead of just id

List the the dates of the matches and the name of the team in which 'Fernando Santos' was the team1 coach.

SELECT mdate,teamname
FROM game
JOIN eteam ON(game.team1=eteam.id)
WHERE coach='Fernando Santos'

7.List the player for every goal scored in a game where the stadium was 'National Stadium, Warsaw'

逗号后一个空格

SELECT player
FROM goal
JOIN game ON(matchid = id)
WHERE stadium ='National Stadium, Warsaw'

8.The example query shows all goals scored in the Germany-Greece quarterfinal.

Instead show the name of all players who scored a goal against Germany.

HINT
Select goals scored only by non-German players in matches where GER was the id of either team1 or team2.

You can use teamid!='GER' to prevent listing German players.

You can use DISTINCT to stop players being listed twice.

SELECT DISTINCT(player)
  FROM game JOIN goal ON matchid = id 
    WHERE (team1='GER' OR team2='GER') AND teamid!='GER'

9.Show teamname and the total number of goals scored.

SELECT teamname,COUNT(1)
FROM goal JOIN eteam ON(teamid=id)
GROUP BY teamname 

10.Show the stadium and the number of goals scored in each stadium.

SELECT stadium,COUNT(1)
FROM game JOIN goal ON(matchid=id)
GROUP BY stadium

11.For every match involving 'POL', show the matchid, date and the number of goals scored.

SELECT matchid,mdate,COUNT(1)
FROM game JOIN goal ON(matchid=id)
WHERE team1='POL' OR team2='POL'
GROUP BY matchid

12.For every match where 'GER' scored, show matchid, match date and the number of goals scored by 'GER'

SELECT matchid,mdate,COUNT(1)
FROM game JOIN goal ON(matchid=id)
WHERE (team1='GER'OR team2='GER')
AND teamid='GER'
GROUP BY matchid

13.List every match with the goals scored by each team as shown. This will use "CASE WHEN" which has not been explained in any previous exercises.

mdate team1 score1 team2 score2
1 July 2012 ESP 4 ITA 0
10 June 2012 ESP 1 ITA 1
10 June 2012 IRL 1 CRO 3
...
Notice in the query given every goal is listed. If it was a team1 goal then a 1 appears in score1, otherwise there is a 0. You could SUM this column to get a count of the goals scored by team1. Sort your result by mdate, matchid, team1 and team2.

SELECT mdate,team1,
SUM(CASE WHEN team1=teamid THEN 1 ELSE 0 END) score1,
team2,
SUM(CASE WHEN team2=teamid THEN 1 ELSE 0 END) score2 
FROM game
LEFT JOIN goal ON(id=matchid)
GROUP BY id
ORDER BY mdate,matchid,team1,team2

7.More JOIN

1.List the films where the yr is 1962 [Show id, title]

SELECT id,title
FROM movie
WHERE yr=1962

2.Give year of 'Citizen Kane'.

SELECT yr
FROM movie
WHERE title ='Citizen Kane'

3.List all of the Star Trek movies, include the id, title and yr (all of these movies include the words Star Trek in the title). Order results by year.

SELECT id,title,yr
FROM movie
WHERE title LIKE "%Star Trek%"
ORDER BY yr

4.What id number does the actor 'Glenn Close' have?

SELECT id
FROM actor
WHERE name='GLenn Close'

5.What is the id of the film 'Casablanca'

SELECT id
FROM movie
WHERE title='Casablanca'

6.Obtain the cast list for 'Casablanca'.

what is a cast list?
Use movieid=11768, (or whatever value you got from the previous question)

SELECT name
FROM movie m,actor a,casting c
WHERE m.id=c.movieid 
AND a.id =c.actorid
AND m.id = 11768

7.Obtain the cast list for the film 'Alien'

SELECT name
FROM movie m,actor a,casting c
WHERE m.id=c.movieid 
AND a.id =c.actorid
AND m.title = 'Alien'

8.List the films in which 'Harrison Ford' has appeared

SELECT m.title
FROM movie m,actor a,casting c
WHERE m.id=c.movieid
AND a.id = c.actorid
AND a.name='Harrison Ford'

9.List the films where 'Harrison Ford' has appeared - but not in the starring role. [Note: the ord field of casting gives the position of the actor. If ord=1 then this actor is in the starring role]

SELECT title
FROM casting c
JOIN actor a ON (c.actorid=a.id)
JOIN movie m ON (c.movieid=m.id)
AND a.name='Harrison Ford'
AND c.ord<>1

10.List the films together with the leading star for all 1962 films.

SELECT m.title,a.name
FROM actor a
JOIN casting c ON(a.id=c.actorid)
JOIN movie m ON(m.id=c.movieid)
AND yr=1962
AND c.ord=1

11.Which were the busiest years for 'Rock Hudson', show the year and the number of movies he made each year for any year in which he made more than 2 movies.

SELECT yr,COUNT(m.title)
FROM movie m
JOIN casting c ON(m.id=c.movieid)
JOIN actor a ON(a.id= c.actorid)
WHERE a.name='Rock Hudson'
GROUP BY yr
HAVING COUNT(m.title)>2

12.List the film title and the leading actor for all of the films 'Julie Andrews' played in. 好题

Julie Andrews starred in the 1980 remake of Little Miss Marker and not the original(1934).

Title is not a unique field, create a table of IDs in your subquery
这个人参演了两部同名的电影

SELECT m.title,a.name
FROM movie m 
JOIN casting c ON(m.id = c.movieid)
JOIN actor a ON(c.actorid = a.id)
WHERE c.ord=1 AND m.id IN
(SELECT m.id AS mid
FROM movie m 
JOIN casting c ON(m.id = c.movieid)
JOIN actor a ON(c.actorid = a.id)
WHERE a.name='Julie Andrews')

13.Obtain a list, in alphabetical order, of actors who've had at least 15 starring roles.

SELECT a.name
FROM casting c 
JOIN movie m ON(c.movieid=m.id)
JOIN actor a ON(c.actorid=a.id)
WHERE c.ord=1
GROUP BY a.name
HAVING COUNT(m.id)>=15
ORDER BY a.name

14.List the films released in the year 1978 ordered by the number of actors in the cast, then by title.

SELECT m.title,COUNT(a.id)
FROM movie m
JOIN casting c ON (m.id=c.movieid)
JOIN actor a ON (c.actorid=a.id)
WHERE m.yr=1978
GROUP BY m.title
ORDER BY COUNT(a.id) DESC,title

15.List all the people who have worked with 'Art Garfunkel'.

SELECT a.name
FROM casting c 
JOIN actor a ON (c.actorid=a.id)
JOIN movie m ON (c.movieid=m.id)
WHERE a.name!='Art Garfunkel' 
AND m.id
IN(
SELECT m.id
FROM casting c 
JOIN actor a ON (c.actorid=a.id)
JOIN movie m ON (c.movieid=m.id)
WHERE a.name='Art Garfunkel')

8.Using Null

1.List the teachers who have NULL for their department.

Why we cannot use =
You might think that the phrase dept=NULL would work here but it doesn't - you can use the phrase dept IS NULL

That's not a proper explanation.

SELECT name
FROM teacher
WHERE dept is NULL

2.Note the INNER JOIN misses the teachers with no department and the departments with no teacher.

SELECT t.name,d.name
FROM teacher t
INNER JOIN  dept d ON(t.dept = d.id)

3.Use a different JOIN so that all teachers are listed.

SELECT t.name,d.name
FROM teacher t
LEFT JOIN dept d ON(t.dept=d.id)

4.Use a different JOIN so that all departments are listed.

SELECT t.name,d.name
FROM teacher t
RIGHT JOIN dept d ON(t.dept = d.id)

5.Use COALESCE to print the mobile number. Use the number '07986 444 2266' if there is no number given. Show teacher name and mobile number or '07986 444 2266'

SELECT name,COALESCE(mobile,'07986 444 2266')
FROM teacher

6.Use the COALESCE function and a LEFT JOIN to print the teacher name and department name. Use the string 'None' where there is no department.

SELECT t.name,COALESCE(d.name,'None')
FROM teacher t
LEFT JOIN dept d ON(t.dept=d.id)

7.Use COUNT to show the number of teachers and the number of mobile phones.

SELECT COUNT(name),COUNT(mobile)
FROM teacher

8.Use COUNT and GROUP BY dept.name to show each department and the number of staff. Use a RIGHT JOIN to ensure that the Engineering department is listed.

SELECT d.name,COUNT(t.name)
FROM teacher t
RIGHT JOIN dept d ON(t.dept = d.id)
GROUP BY d.name

9.Use CASE to show the name of each teacher followed by 'Sci' if the teacher is in dept 1 or 2 and 'Art' otherwise.

SELECT t.name,
CASE WHEN(t.dept IN(1,2)) THEN "Sci"
ELSE "Art"
END
FROM teacher t
LEFT JOIN dept d ON(t.dept=d.id)

10.Use CASE to show the name of each teacher followed by 'Sci' if the teacher is in dept 1 or 2, show 'Art' if the teacher's dept is 3 and 'None' otherwise.

SELECT t.name,
CASE WHEN(t.dept=1 OR t.dept=2) THEN "Sci"
     WHEN(t.dept=3)THEN "Art"
ELSE "None"
END
FROM teacher t
LEFT JOIN dept d ON(t.dept=d.id)

9.SELF JOIN

1.How many stops are in the database.

SELECT COUNT(*)
FROM stops

2.Find the id value for the stop 'Craiglockhart'

SELECT id
FROM stops s
WHERE s.name ='Craiglockhart'

3.Give the id and the name for the stops on the '4' 'LRT' service.