The JOIN operation

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

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

3. 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 id = teamid
WHERE gtime<=10;

6. List 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 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’.

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

8. Show the name of all players who scored a goal against Germany.

//射入德国球门的球员姓名（主队是德国或者客队是德国）
SELECT distinct player
FROM game JOIN goal ON matchid = id 
WHERE (teamid = team1 AND team2 = 'GER')
OR (teamid = team2 AND team1 = 'GER');

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

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

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

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

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

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

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

SELECT matchid,mdate,COUNT(gtime)
FROM game
JOIN goal
ON id = matchid
WHERE teamid = 'GER'
GROUP BY matchid,mdate;

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