4

在找不到任何符合我需要的东西后，我编写了这段代码来一致地打乱 mysql 中列的值。有一个更好的方法吗？

**Original table:**
+----+-----------+
| id | fname     |
+----+-----------+
|  1 | mike      |
|  2 | ricky     |
|  3 | jane      |
|  4 | august    |
|  6 | dave      |
|  9 | Jérôme    |
+----+-----------+

**Possible output:**
+----+-----------+
| id | fname     |
+----+-----------+
|  1 | dave      |
|  2 | jane      |
|  3 | mike      |
|  4 | ricky     |
|  6 | Jérôme    |
|  9 | august    |
+----+-----------+

DROP TEMPORARY TABLE IF EXISTS shuffle1;
DROP TEMPORARY TABLE IF EXISTS shuffle2;
CREATE TEMPORARY TABLE shuffle1 (id int(11) NOT NULL AUTO_INCREMENT, PRIMARY KEY (id), original_values varchar(255), key original_values(original_values) );
CREATE TEMPORARY TABLE shuffle2 (id int(11) NOT NULL AUTO_INCREMENT, PRIMARY KEY (id), original_ids int(11), key original_ids(original_ids) );
INSERT INTO shuffle1 (id, original_values) SELECT NULL, table1.fname FROM table1 ORDER BY rand();
INSERT INTO shuffle2 (id, original_ids) SELECT NULL, table1.id FROM table1;
UPDATE table1 SET table1.fname = (SELECT shuffle1.original_values FROM shuffle1 JOIN shuffle2 ON shuffle2.id = shuffle1.id WHERE table1.id = shuffle2.original_ids);
4

2 回答 2

0

如果您不介意某些表格数据无法处理（取决于表格大小，预计 50% 的行无法处理），这里有一个解决方案：

原始表

id  name
1   Some
2   Body
3   Once
4   Told
5   Me
6   The
7   World
8   Is
9   Gonna
10  Roll
11  Me
12  I 
13  Ain't
14  The 
15  Shapest
16  Tool
17  In
18  The
19  Shed
20  She
21  was
22  looking
23  kind
24  of
25  dumb
26  with
27  her
28  finger
29  and
30  her
31  thumb

询问：

SELECT new_id, name FROM (
    SELECT  new_id, name FROM (
        SELECT new_meme.id as new_id, original_meme.id as original_id, original_meme.name FROM meme original_meme
        JOIN meme new_meme ON new_meme.id <>  original_meme.id
        ORDER BY RAND()
    ) layer1
    GROUP BY layer1.new_id
) layer2 GROUP BY name

结果（当然每次运行都不同）

1   I 
2   In
3   Gonna
4   Ain't
5   The
6   her
7   finger
8   Some
9   dumb
10  She
15  Me
16  with
17  Told
18  and
19  World
21  Roll
22  The 
25  Tool
26  Shed
27  Is
28  Me
29  Sharpest
31  The

注意：您可能会发现查询很慢，这是因为它两次加入表，所以如果数据大小为 1000，则需要处理 1000 * 1000。

您可以通过 chagingON new_meme.id <> original_meme.id来控制查询的速度ON new_meme.id BETWEEN original_meme.id - 5 AND original_meme.id +5（5 可以更改），但它会降低随机性并且不适用于非数字 id

于 2019-01-15T04:34:39.030 回答
-1 
UPDATE table1 SET fname=(SELECT t.fname FROM(SELECT fname FROM table1) t ORDER BY RAND() LIMIT 1)
于 2014-01-15T10:56:16.707 回答