Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
356 views
in Technique[技术] by (71.8m points)

foreign keys - How to select SQL results based on multiple tables

I need to select results from one table based on certain matching values in a couple of other tables. I have the following tables:

person: id, firstname, lastname
team: id, teamname
player: id, person_id(FK), team_id(FK)
coach: id, person_id(FK), team_id(FK)

I need to return all the coaches and players names for each team. I've only ever used inner joins, and it doesn't seem like I can use those here, so any idea how to do this?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

This will give you the coach:

SELECT team.Teamname, person.Firstname, person.Lastname
FROM person
JOIN coach ON person.id = coach.person_id
JOIN team  ON coach.team_id = team.id

And this will give you the players:

SELECT team.Teamname, person.Firstname, person.Lastname
FROM person
JOIN player ON person.id = player.person_id
JOIN team  ON player.team_id = team.id

So, the non-elegant, simple answer is to just toss it all together with UNION.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...