计算 2 列的发生次数

Question

所以基本上，我需要一个查询来 return 显示名称、杀戮数量和死亡数量。

我有两个 table 需要从中提取。

两个table是

player

id      | name
2334324 | user
4353454 | user2

其中 id 是他们的唯一标识符，name 是他们的显示名称。

第二个table是：

player_kill

id | killer  | victim  |
1  | 2334324 | 4353454 |
2  | 2334324 | 4353454 |  
3  | 4353454 | 2334324 |

其中 killer / victim 列包含 player table.

的唯一标识符

我希望能够计算 killer 和 victim 中玩家 ID 的出现次数，以便查询 returns:

name | kills | deaths
user | 2     | 1
user2| 1     | 2

其中，击杀数不足的是 playerid 在 killer 列中出现的次数，死亡人数也是如此

希望我提供了足够的信息。

我目前拥有的：

SELECT `player`.`name`, COUNT(DISTINCT `player_kill`.`id`) as `kills`, COUNT(DISTINCT `player_kill`.`id`) as `deaths`
FROM `player`
LEFT JOIN `player_kill` ON `player`.`id`=`player_kill`.`killer`
LEFT JOIN `player_kill` ON `player`.`id`=`player_kill`.`victim`
WHERE `player`.`id` = `player_kill`.`killer` AND `player`.`id` = `player_kill`.`victim`
GROUP BY `player`.`id`;

Answer 1

尝试

SELECT 
    p.name, 
    count(distinct pk1.id) as kills, 
    count(distinct pk2.id) as deaths
FROM player p
LEFT JOIN player_kill pk1 ON pk1.killer = p.id 
LEFT JOIN player_kill pk2 ON pk2.victim = p.id 
group by p.name

http://sqlfiddle.com/#!9/649504/15/0

Answer 2

看看这是否有效：

SELECT  `player`.`name`,
        COUNT(DISTINCT k.`id`) as `kills`,
        COUNT(DISTINCT v.`id`) as `deaths`
    FROM  `player`
    LEFT JOIN  `player_kill` AS k ON `player`.`id` = k.`killer`
    LEFT JOIN  `player_kill` AS v ON `player`.`id` = v.`victim`
    GROUP BY  `player`.`id`;

如果没有，那么我们可能需要将 COUNT 做成子查询。

计算 2 列的发生次数

Count 2 columns for occurrence

mysql

sql

innodb