我想从下表中选择fname列中具有相似值的所有行作为它们的顺序中的第一行.从这张表中我想要检索带有ids 2,5和7的行(因为“anna”出现在“anna”之后,而“michaela”和“michaal”出现在“michael”之后).
+----+------------+----------+
| id | fname | lname |
+----+------------+----------+
| 1 | anna | milski |
| 2 | anna | nguyen |
| 3 | michael | michaels |
| 4 | james | bond |
| 5 | michaela | king |
| 6 | bruce | smart |
| 7 | michaal | hardy |
+----+------------+----------+
到目前为止我所拥有的是:
select *, count(fname) cnt
from users group by soundex(fname)
having count(soundex(fname)) > 1;
但是因为我正在对它进行分组,结果是
+----+----------+----------+-----+
| id | fname | lname | cnt |
+----+----------+----------+-----+
| 1 | anna | milski | 2 |
| 3 | michael | michaels | 3 |
+----+----------+----------+-----+
我想要检索的是:
+----+----------+----------+-----+
| id | fname | lname | cnt |
+----+----------+----------+-----+
| 2 | anna | nyugen | 2 |
| 5 | michaela | king | 3 |
| 7 | michaal | hardy | 3 |
+----+----------+----------+-----+
我应该对查询做些什么改变?我尝试删除“分组依据”,但它改变了结果(我可能是错的,没有广泛测试).
解决方法:
我已经重新阅读了您的初步问题,我想出了以下解决方案:
SELECT *
FROM users
WHERE id IN
(SELECT id
FROM users t4
INNER JOIN
(SELECT soundex(fname) AS snd,
COUNT(*) AS cnt
FROM users AS t5
GROUP BY snd
HAVING cnt > 1
)
AS t6
ON soundex(t4.fname)=snd
)
AND id NOT IN
(SELECT MIN(t2.id) AS wanted
FROM users t2
INNER JOIN
(SELECT soundex(fname) AS snd,
COUNT(*) AS cnt
FROM users AS t1
GROUP BY snd
HAVING cnt > 1
)
AS t3
ON soundex(t2.fname)=snd
GROUP BY snd
);
这有点过于复杂,但它的工作原理与您提出的要求完全相同:)