SQLzoo刷题记录-The JOIN operation/zh

id(編號)	mdate(日期)	stadium(場館)	team1(隊伍1)	team2(隊伍2)
1001	8 June 2012	National Stadium, Warsaw	POL	GRE
1002	8 June 2012	Stadion Miejski (Wroclaw)	RUS	CZE
1003	12 June 2012	Stadion Miejski (Wroclaw)	GRE	CZE
1004	12 June 2012	National Stadium, Warsaw	POL	RUS
...

goal(入球)
matchid(賽事編號)	teamid(隊伍編號)	player(入球球員)	gtime(入球時間)
1001	POL	Robert Lewandowski	17
1001	GRE	Dimitris Salpingidis	51
1002	RUS	Alan Dzagoev	15
1001	RUS	Roman Pavlyuchenko	82
...

eteam(歐洲隊伍)
id(編號)	teamname(隊名)	coach(教練)
POL	Poland	Franciszek Smuda
RUS	Russia	Dick Advocaat
CZE	Czech Republic	Michal Bilek
GRE	Greece	Fernando Santos
...

1.列出賽事編號matchid 和球員名 player ,該球員代表德國隊Germany入球的。要找出德國隊球員，要檢查: teamid = 'GER'

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

2.只顯示賽事1012的 id, stadium, team1, team2

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

3.顯示每一個德國入球的球員名，隊伍名，場館和日期。

SELECT s.player,s.teamid,t.stadium,t.mdate
  FROM game t JOIN goal s ON (t.id=s.matchid) where s.teamid = 'GER'

4.列出球員名字叫Mario (player LIKE 'Mario%')有入球的隊伍1 team1, 隊伍2 team2 和球員名 player

select t.team1,t.team2,s.player from game t join goal s on (t.id=s.matchid) 
where s.player LIKE 'Mario%'

5.列出每場球賽中首10分鐘gtime<=10有入球的球員 player, 隊伍teamid, 教練coach, 入球時間gtime

SELECT t.player, t.teamid, s.coach,t.gtime
  FROM goal t join eteam s on t.teamid=s.id
 WHERE t.gtime<=10

6.列出'Fernando Santos'作為隊伍1 team1 的教練的賽事日期，和隊伍名。

select t.mdate,s.teamname from game t join eteam s on t.team1= s.id
 where s.coach='Fernando Santos'

7.列出場館 'National Stadium, Warsaw'的入球球員

select s.player from game t join goal s on t.id=s.matchid
 where t.stadium='National Stadium, Warsaw'

8. 修改它，只列出全部賽事，射入德國龍門的球員名字。

select distinct(player) from game t join goal s on t.id=s.matchid
where (t.team1='GER'or t.team2='GER')
and s.teamid!='GER'

#select distinct(player) from game t join goal s on t.id=s.matchid
where (t.team1=s.teamid and t.team2='GER') or (t.team2=s.teamid and t.team1='GER')

9.列出隊伍名稱 teamname 和該隊入球總數

select t.teamname, count(s.teamid)
  from eteam t join goal s on t.id=s.teamid
 group by teamname

10.列出場館名和在該場館的入球數字。

select t.stadium, count(s.teamid)
  from game t join goal s on t.id=s.matchid
 group by stadium

11.每一場波蘭'POL'有參與的賽事中，列出賽事編號 matchid, 日期date 和入球數字。

SELECT s.matchid,t.mdate,count(s.teamid)
  FROM game t JOIN goal s ON s.matchid = t.id 
 WHERE (t.team1 = 'POL' OR t.team2 = 'POL')
group by s.matchid,t.mdate

12.每一場德國'GER'有參與的賽事中，列出賽事編號 matchid, 日期date 和德國的入球數字。

SELECT s.matchid,t.mdate,count(s.teamid)
  FROM game t JOIN goal s ON s.matchid = t.id 
 WHERE (t.team1 = 'GER' OR t.team2 = 'GER') and s.teamid='GER'
group by s.matchid,t.mdate

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.

SELECT distinct 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 t left JOIN goal s ON t.id=s.matchid 
group by t.mdate,s.matchid,t.team1,team2