自连接以查找重复项但包括所有列

Question

我想匹配日志 table 中出现的具有相同 day 和 cause 且在 table 中出现不止一次的任何条目。我编写的查询已经获取了重复项，我的问题是我需要访问 table 结果中的所有列以用于以后的 JOIN。 Table 看起来像这样：

| ID | DATE       | CAUSE | USER | ... |
|--------------------------------------|
| x  | 2017-01-01 | aaa   | 100  | ... |
| x  | 2017-01-02 | aaa   | 101  | ... |
| x  | 2017-01-03 | bbb   | 101  | ... |
| x  | 2017-01-03 | bbb   | 101  | ... |
| x  | 2017-01-04 | ccc   | 101  | ... |
| x  | 2017-01-04 | ccc   | 101  | ... |
| x  | 2017-01-04 | ccc   | 101  | ... |
| x  | 2017-01-05 | aaa   | 101  | ... |
| .....................................|
| .....................................|
| .....................................|

查询：

SELECT logs.* FROM 
    (SELECT day, cause FROM logs 
         GROUP BY day, cause HAVING COUNT(*) > 1) AS logsTwice, logs 
WHERE logsTwice.day = logs.day AND logsTwice.cause = logs.cause

sub select 获取了完全正确的数据（日期和原因），但是当我尝试获取这些匹配项的其他列时，我得到了完全错误的数据。我做错了什么？

Answer 1

试试这个：

SELECT logs.* FROM logs
inner join 
(SELECT day, cause FROM logs GROUP BY day, cause HAVING COUNT(*) > 1) logsTwice
on logsTwice.day = logs.day AND logsTwice.cause = logs.cause

Answer 2

您可以只使用 window 函数：

SELECT l.*
FROM (SELECT l.*,
             COUNT(*) OVER (PARTITION BY day, cause) as cnt
      FROM logs l
     ) l
WHERE cnt > 1;

一般来说，window 函数的性能优于使用 JOIN 和 GROUP BY 的等效查询。

Answer 3

你可以试试

SELECT l1.*
  FROM logs l1
 INNER JOIN logs l2
    ON (l1.id <> l2.id
        AND l1.day = l2.day
        AND l1.cause = l2.cause
        AND l1.user <> l2.user);

自连接以查找重复项但包括所有列

Self Join to find duplicates but including all columns

sql

join

self-join