[英]SQL count two columns and substract
晚安。 我遇到了这个问题,我尝试了子查询和案例,但没有成功。
当玩家在我的游戏中杀死某人时,会在数据库中添加一条新记录,该记录包含杀手的 ID 和被杀死的玩家的 ID,因此一段时间后表将如下所示:
killer_id | death_id
100 | 200 -> (Player 100 Killed player 200)
100 | 200
100 | 200
200 | 100
300 | 100
300 | 200
我试图根据他们的杀戮减去他们的死亡来获得每个玩家的分数,因此基于上述数据:
Rank:
Pos 1. player 300 / 2 Points (2 Kills - 0 deaths)
Pos 2. player 100 / 1 Point (3 Kills - 2 deaths)
Pos 3. player 200 / -3 Points (1 Kills - 4 deaths)
我想在一个 SQL 查询上执行此操作,但我被卡住了……任何提示都将不胜感激。
您可以使用union all
和聚合:
select player_id, sum(cnt) score
from (
select killer_id player_id, 1 cnt from mytable
union all select death_id, -1 from mytable
) t
group by player_id
order by score desc
如果你还想要玩家排名,你可以使用窗口函数(这需要 MySQL 8.0):
select rank() over(order by sum(cnt) desc) pos, player_id, sum(cnt) score
from (
select killer_id player_id, 1 cnt from mytable
union all select death_id, -1 from mytable
) t
group by player_id
order by score desc
您可以使用union all
和聚合:
select player_id, sum(points)
from ((select killer_id as player_id, 1 as points
from t
) union all
(select death_id, -1 as points
from t
)
) kd
group by player_id
order by sum(points) desc;
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.