Retrieving data from a database with relationships

Question

I am trying to retrieve some data from my database, I have already made the right relationships inside the database but I just can't get my head around which query to use.

Here is a visual representation of the different relationships:

What I want is to get all data from clanwars aswel as all usernames from the users who have applied for these wars.

Can you guys help me?

Thanks in advance!

Answer 1

How about:

select w.*, m.username
  from clanwars w
  join applications a on a.warid = w.id
  join members m on m.id = a.playerid

Answer 2

All data from clan wars:

select * from clanwars;

All users that have applied to participate in a certain war:

select playerid from applications where warid = <war_id>;

Make sure to replace war_id with the desired war id you want to pull playerid's from.

All users that have applied to a war at all:

select distinct playerid from applications;

All usernames that have applied to a war (using a subquery):

select username from members where id in (select distinct playerid from applications);

My go to SQL resource is www.w3schools.com/sql/ . Check it out when you get a chance.