目前我的查询如下所示：
SELECT alias.name killer,
SUM(kill_stats.amount) amount
FROM kill_stats
JOIN pickup ON pickup.logfile = 'CTFCL-20130813-1456-shutdown2'
JOIN account ON account.steam_id = '0:1:705272'
JOIN player victim ON victim.pickup_id = pickup.id AND victim.account_id = account.id
JOIN player killer ON killer.pickup_id = pickup.id AND kill_stats.killer_id = killer.id
JOIN alias ON killer.alias_id = alias.id
WHERE kill_stats.victim_id = victim.id AND NOT killer.team_id = victim.team_id
GROUP BY kill_stats.killer_id
ORDER BY amount DESC
kill_stats表布局：
CREATE TABLE `kill_stats` (
`killer_id` int(11) UNSIGNED NOT NULL,
`victim_id` int(11) UNSIGNED NOT NULL,
`weapon_id` int(11) UNSIGNED NOT NULL,
`conced` bit(1) NOT NULL,
`fc` bit(1) NOT NULL,
`amount` int(11) UNSIGNED NOT NULL,
PRIMARY KEY(`killer_id`, `victim_id`, `weapon_id`, `conced`, `fc`),
CONSTRAINT `Ref_Killer` FOREIGN KEY (`killer_id`)
REFERENCES `player`(`id`)
ON DELETE CASCADE
ON UPDATE CASCADE,
CONSTRAINT `Ref_Victim` FOREIGN KEY (`victim_id`)
REFERENCES `player`(`id`)
ON DELETE CASCADE
ON UPDATE CASCADE,
CONSTRAINT `Ref_Weapon` FOREIGN KEY (`weapon_id`)
REFERENCES `weapon`(`id`)
ON DELETE CASCADE
ON UPDATE CASCADE
)
ENGINE=INNODB
CHARACTER SET utf8
COLLATE utf8_unicode_ci ;
这是一个更易读的视图，用虚拟数据替换外键：
+-----------+-----------+-----------+--------+----+--------+
| killer_id | victim_id | weapon_id | conced | fc | amount |
+-----------+-----------+-----------+--------+----+--------+
| Josephine | Frank | RPG | NO | NO | 14 |
+-----------+-----------+-----------+--------+----+--------+
| Josephine | Frank | Shotgun | YES | NO | 5 |
+-----------+-----------+-----------+--------+----+--------+
| Josephine | Frank | Shotgun | NO | NO | 3 |
+-----------+-----------+-----------+--------+----+--------+
| Miguel | Frank | Knife | NO | NO | 1 |
+-----------+-----------+-----------+--------+----+--------+
使用此示例表，上面的查询将返回如下表：
+-----------+--------+
| killer | amount |
+-----------+--------+
| Josephine | 22 |
+-----------+--------+
| Miguel | 1 |
+-----------+--------+
我希望输出是：
+-----------+-------------+--------------+-----------------+
| killer | total_kills | conced_kills | victim_had_flag |
+-----------+-------------+--------------+-----------------+
| Josephine | 22 | 5 | 0 |
+-----------+-------------+--------------+-----------------+
| Miguel | 1 | 0 | 0 |
+-----------+-------------+--------------+-----------------+
显示某个玩家被其他玩家杀死的频率、他们杀死他的总次数、被承认的杀死数量以及玩家在被他们杀死时携带旗帜的频率。
我不太确定如何做到这一点，我已经尝试过GROUP BY kill_stats.killer_id, kill_stats.conced，但结果是：
+-----------+--------+
| killer | amount |
+-----------+--------+
| Josephine | 14 | -> the ones with kill_stats.conced = NO
+-----------+--------+
| Josephine | 5 | -> the ones with kill_stats.conced = YES
+-----------+--------+
| Miguel | 1 | -> the ones with kill_stats.conced = NO (only row for that `killer_id`)
+-----------+--------+
我得到多行killer_id，我希望每行killer_id保存所有数据。
Ike Walker的解决方案几乎是我一直在寻找的，使其按我想要的方式工作的最终查询是：
SELECT alias.name killer,
SUM(kill_stats.amount) as total_kills ,
SUM(CASE WHEN kill_stats.conced then kill_stats.amount ELSE 0 END) as conced_kills ,
SUM(CASE WHEN kill_stats.fc then kill_stats.amount ELSE 0 END) as victim_had_flag
FROM kill_stats
JOIN pickup ON pickup.logfile = 'CTFCL-20130813-1456-shutdown2'
JOIN account ON account.steam_id = '0:1:705272'
JOIN player victim ON victim.pickup_id = pickup.id AND victim.account_id = account.id
JOIN player killer ON killer.pickup_id = pickup.id AND kill_stats.killer_id = killer.id
JOIN alias ON killer.alias_id = alias.id
WHERE kill_stats.victim_id = victim.id AND NOT killer.team_id = victim.team_id
GROUP BY kill_stats.killer_id
ORDER BY amount DESC
他的解决方案最终使我走上正轨的不同之处在于，对于将列设置为 1的每一行，我总是需要将SUM() kill_stats.amount放入新列中。conced_killsBIT(1)