SQL连接未正常工作旺旺

Question

我有两个表像

洛表

+-------------+---------+---------+-----+ 
| player_name | user_id | tour_id | los | 
+-------------+---------+---------+-----+ 
| P1   |  1 |  3 | 1 | 
| P2   |  1 |  3 | 3 | 
| P3   |  1 |  3 | 2 | 
| P4   |  1 |  3 | 2 | 
| P5   |  1 |  3 | 2 | 
| P6   |  1 |  3 | 1 | 
| P7   |  1 |  3 | 1 | 
| P8   |  1 |  3 | 0 | 
+-------------+---------+---------+-----+ 

而且

运表

+-------------+---------+---------+-----+ 
| player_name | user_id | tour_id | win | 
+-------------+---------+---------+-----+ 
| P1   |  1 |  3 | 2 | 
| P2   |  1 |  3 | 0 | 
| P3   |  1 |  3 | 1 | 
| P4   |  1 |  3 | 1 | 
| P5   |  1 |  3 | 1 | 
| P6   |  1 |  3 | 2 | 
| P7   |  1 |  3 | 2 | 
| P8   |  1 |  3 | 3 | 
+-------------+---------+---------+-----+ 

而且我想球员姓名，洛杉矶从第一，从第二赢得

我想集团被球员的名字，但它会出现误导结果

select player_name, los.los, win.win 
from los,win 
group by player_name; 

Answer 1

只要你加入，必须有一个加盟条件否则它会做一个笛卡尔乘积。

select los.player_name, sum(los.los), sum(win.win) 
from los,win 
where los.player_name = win.player_name 
group by los.player_name;