查找表排名在比賽

Question

我有2個表

create table players 
(name text, 
id serial primary key); 

create table matches 
(winner integer references players(id), 
    loser integer references players(id), 
    id serial primary key); 

我必須做出一個名爲「榜」含表：

player_id,player_name,total_wins,total_matches 

如何進行？

Answer 1

事情是這樣的：

select p.id, p.name, 
     count(w.id) as total_wins, 
     count(l.id) + count(w.id) as total_matches 
from players p 
    left join matches w on w.winner = p.id 
    left join matches l on l.loser = p.id 
group by p.id, p.name; 

在線例如：http://rextester.com/EHDCG19917