Question

我正在使用MySQL

我有三张桌子：

accounts {
    account_id,
    username
}

account_ips {
    idaccount_ips,
    account_id,
    ip
}

account_bans {
    ban_id
    account_id,
    expires
}

需要获得不在禁止表中的每个ip的帐户的分组计数。（见下面的查询）

我尝试了以下内容，但速度太慢（44秒）：

SELECT DISTINCT a.account_id, count(DISTINCT a.account_id)
  FROM account_ips AS a
 WHERE NOT EXISTS(
    SELECT 1
      FROM account_bans AS b
     WHERE b.expires > 1340341272 AND b.account_id = a.account_id)
 GROUP BY a.ip
HAVING count(DISTINCT a.account_id) > 3
 ORDER BY count(DISTINCT a.account_id) DESC;

解释输出如下：

1, 'PRIMARY', 'a', 'ALL', '', '', '', '', 304745, 'Using where; Using temporary; Using filesort'
2, 'DEPENDENT SUBQUERY', 'b', 'ALL', '', '', '', '', 1851, 'Using where'

Answer 1

你需要这样做 -

SELECT AIP.IP, COUNT(AIP.ACCOUNT_ID)
FROM ACCOUNT_IPS AIP
LEFT JOIN ACCOUNTS A ON AIP.ACCOUNT_ID=A.ACCOUNT_ID
LEFT JOIN ACCOUNT_BANS AB ON A.ACCOUNT_ID=AB.ACCOUNT_ID
WHERE
AB.BAN_ID IS NULL
GROUP BY AIP.IP

如果您还需要考虑b.expires＆gt; 1340341272然后查询将是 -

SELECT AIP.IP, COUNT(AIP.ACCOUNT_ID)
FROM ACCOUNT_IPS AIP
LEFT JOIN ACCOUNTS A ON AIP.ACCOUNT_ID=A.ACCOUNT_ID
LEFT JOIN ACCOUNT_BANS AB ON A.ACCOUNT_ID=AB.ACCOUNT_ID
WHERE
AB.BAN_ID IS NULL
OR AB.EXPIRES <= 1340341272
GROUP BY AIP.IP

Answer 2

尝试left join并在右表中获取ips的空值，而不是WHERE NOT EXISTS。

FROM account_ips a
LEFT JOIN account_bans b ON b.account_id = a.account_id
WHERE b.account_id IS NULL

SQL性能查询，用于检查多个表中的值

2 个答案: