在用 SELECT 查询的时候，如果用到了 IN ，那么查询结果中的顺序并不是按照 IN 后面所给的顺序返回，而是按照默认的升序排列。如下：
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mysql> SELECT * FROM test WHERE id IN (343,123,32,10,6,981,651,98,129);
|
02 |
+-----+--------+ |
03 |
| id | name |
|
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+-----+--------+ |
05 |
| 6 | URdhMl | |
06 |
| 10 | Xl[hJq | |
07 |
| 32 | u^]~%p | |
08 |
| 98 | Uq`InZ | |
09 |
| 123 | yv](Ff | |
10 |
| 129 | Owx_mt | |
11 |
| 343 | =P3w,m | |
12 |
| 651 | zR!yD= | |
13 |
| 981 | 5%$EuH | |
14 |
+-----+--------+ |
15 |
9 rows in set (0.00 sec)
|
而如果想要让查询结果按照 IN 里面给的顺序的话，这里有几种方法：
转自：@喵了个咪
一、使用 FIND_IN_SET 建立一个派序列：
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mysql> SELECT * FROM test WHERE id IN (343,123,32,10,6,981,651,98,129) ORDER BY FIND_IN_SET(id,'343,123,32,10,6,981,651,98,129');
|
02 |
+-----+--------+ |
03 |
| id | name |
|
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+-----+--------+ |
05 |
| 343 | =P3w,m | |
06 |
| 123 | yv](Ff | |
07 |
| 32 | u^]~%p | |
08 |
| 10 | Xl[hJq | |
09 |
| 6 | URdhMl | |
10 |
| 981 | 5%$EuH | |
11 |
| 651 | zR!yD= | |
12 |
| 98 | Uq`InZ | |
13 |
| 129 | Owx_mt | |
14 |
+-----+--------+ |
15 |
9 rows in set (0.00 sec)
|
下面这样可以看到 FIND_IN_SET 的操作方式：也就是 FIND_IN_SET 这个函数返回一个 1-n 递增的字符串，而ORDER BY 这个字符串就相当于是按升序排列了，而这个 1-n 对应着给入的那些 id
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mysql> SELECT id,name,FIND_IN_SET(id,'343,123,32,10,6,981,651,98,129') AS sort_order FROM test WHERE id IN (343,123,32,10,6,981,651,98,129) ORDER BY FIND_IN_SET(id,'343,123,32,10,6,981,651,98,129');
|
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+-----+--------+------------+ |
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| id | name | sort_order |
|
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+-----+--------+------------+ |
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| 343 | =P3w,m | 1 | |
06 |
| 123 | yv](Ff | 2 | |
07 |
| 32 | u^]~%p | 3 | |
08 |
| 10 | Xl[hJq | 4 | |
09 |
| 6 | URdhMl | 5 | |
10 |
| 981 | 5%$EuH | 6 | |
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| 651 | zR!yD= | 7 | |
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| 98 | Uq`InZ | 8 | |
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| 129 | Owx_mt | 9 | |
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+-----+--------+------------+ |
15 |
9 rows in set (0.00 sec)
|
二、自己构建一个顺序 id 表，左连接 IN 查询结果集：
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mysql> SELECT * FROM ( |
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-> SELECT 343 AS id UNION
|
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-> SELECT 123 UNION
|
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-> SELECT 32 UNION
|
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-> SELECT 10 UNION
|
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-> SELECT 6 UNION
|
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-> SELECT 981 UNION
|
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-> SELECT 651 UNION
|
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-> SELECT 98 UNION
|
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-> SELECT 129
|
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-> ) AS table1
|
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-> LEFT JOIN test table2 ON table1.id=table2.id
|
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-> WHERE table2.id IN (343,123,32,10,6,981,651,98,129);
|
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+-----+------+--------+ |
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| id | id | name |
|
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+-----+------+--------+ |
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| 343 | 343 | =P3w,m | |
18 |
| 123 | 123 | yv](Ff | |
19 |
| 32 | 32 | u^]~%p | |
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| 10 | 10 | Xl[hJq | |
21 |
| 6 | 6 | URdhMl | |
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| 981 | 981 | 5%$EuH | |
23 |
| 651 | 651 | zR!yD= | |
24 |
| 98 | 98 | Uq`InZ | |
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| 129 | 129 | Owx_mt | |
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+-----+------+--------+ |
27 |
9 rows in set (0.00 sec)
|
三、使用 UNION ：
01 |
mysql> SELECT * FROM test WHERE id=343 UNION
|
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-> SELECT * FROM test WHERE id=123 UNION
|
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-> SELECT * FROM test WHERE id=32 UNION
|
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-> SELECT * FROM test WHERE id=10 UNION
|
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-> SELECT * FROM test WHERE id=6 UNION
|
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-> SELECT * FROM test WHERE id=981 UNION
|
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-> SELECT * FROM test WHERE id=651 UNION
|
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-> SELECT * FROM test WHERE id=98 UNION
|
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-> SELECT * FROM test WHERE id=129;
|
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+-----+--------+ |
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| id | name |
|
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+-----+--------+ |
13 |
| 343 | =P3w,m | |
14 |
| 123 | yv](Ff | |
15 |
| 32 | u^]~%p | |
16 |
| 10 | Xl[hJq | |
17 |
| 6 | URdhMl | |
18 |
| 981 | 5%$EuH | |
19 |
| 651 | zR!yD= | |
20 |
| 98 | Uq`InZ | |
21 |
| 129 | Owx_mt | |
22 |
+-----+--------+ |
23 |
9 rows in set (0.00 sec)
|