问题描述

我想从下表中选择在 fname 列中具有相似值的所有行作为它们的顺序中的第一行.IOW 从此表中我想检索 id 为 2,5 和 7 的行(因为anna"在anna"和michaela"之后>"和michaal"在michael"之后).

I want to select from the following table all the rows which have similar values in the fname column as the first in their order. IOW from this table I want to retrieve rows with ids 2,5 and 7 (because " anna" comes after "anna", and "michaela" and "michaal" come after "michael").

+----+------------+----------+
| 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:

What I have so far is this:

select *, count(fname) cnt 
from users group by soundex(fname) 
having count(soundex(fname)) > 1;

但由于我将其分组，因此结果是

but since I'm grouping it the result is

+----+----------+----------+-----+
| id | fname    | lname    | cnt |
+----+----------+----------+-----+
|  1 | anna     | milski   |   2 |
|  3 | michael  | michaels |   3 |
+----+----------+----------+-----+

我要检索的是这样的:

+----+----------+----------+-----+
| id | fname    | lname    | cnt |
+----+----------+----------+-----+
|  2 |  anna    | nyugen   |   2 |
|  5 | michaela | king     |   3 |
|  7 | michaal  | hardy    |   3 |
+----+----------+----------+-----+

我应该对查询进行哪些更改?我尝试删除group by"，但它改变了结果(我可能错了，没有进行广泛的测试).

What should I change about the query? I tried removing "group by" but it changes the results (I could be wrong, haven't tested it extensively).

推荐答案

我重新阅读了您最初的问题，并提出了以下解决方案:

I've re-read your initial question and I've came up with the following solution:

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，但它可以工作并且完全符合您的要求:)

It's a bit over-complicated, but it works and delivers exactly what you asked for :)

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