SqlZoo.net习题答案：How to do joins.【Table Tennis】

习题地址：http://sqlzoo.net/3b.htm

表结构：　　ttms(games, color, who, country)
　　　　　　country(id, name)

　　　　　　ttms.county = county.id

1b.Show the who and the color of the medal for the medal winners from 'Sweden'.

select who, color
from ttms join country
on (ttms.country = country.id)
where country.name = 'Sweden'

1c.Show the years in which 'China' won a 'gold' medal.

select games
from ttms join country
on (ttms.country = country.id)
where country.name = 'China' and ttms.color = 'gold'

表结构：　　ttws(games, color, who, country)
　　　　　　games(yr, city, country)

　　　　　　ttws.games = games.yr

2a.Show

who

won medals in the 'Barcelona' games.

select who
from ttws join games
on (ttws.games=games.yr)
where city = 'Barcelona'

2b.Show which city 'Jing Chen' won medals. Show the

city

and the medal

color

.

select games.city, color
from ttws join games
on (ttws.games = games.yr)
where ttws.who = 'Jing Chen'

2c.Show

who

won the gold medal and the

city

.

select ttws.who, games.city
from ttws join games
on (ttws.games = games.yr)
where ttws.color = 'gold'