python | MySQL全面查询的正则匹配

概述

上一章 查询的过滤条件，我们了解了MySQL可以通过 like % 通配符来进行模糊匹配。同样的，它也支持其他正则表达式的匹配，我们在MySQL中使用 REGEXP 操作符来进行正则表达式匹配。用法和like相

似，但又强大很多，能够实现一些很特殊的、复杂的规则匹配。正则表达式使用REGEXP命令进行匹配时，如果符合返回1，不符合返回0。如果 默认不加任何匹配规则REGEXP相当于like '%%'。在前面加上NOT（NOT REGEXP）相当于NOT LIKE。

匹配模式分析

下面有个表格 ，罗列了可应用于 REGEXP 操作符中正则匹配模式，描述相对比较详细了，后面我们一个一个来测试。

匹配模式	描述
^	匹配输入字符串的开始位置。如果设置了 REGEXP 对象的 Multiline 属性，^ 也匹配 ' ' 或 ' ' 之后的位置。
$	匹配输入字符串的结束位置。如果设置了REGEXP 对象的 Multiline 属性，$ 也匹配 ' ' 或 ' ' 之前的位置。
.	匹配除 " " 之外的任何单个字符。要匹配包括 ' ' 在内的任何字符，请使用 '[. ]' 的模式。
[….]	字符集合。匹配所包含的任意一个字符。例如， '[abc]' 可以匹配 "plain" 中的 'a'。
[^...]	非匹配字符集合。匹配未包含的任意字符。例如， '[^abc]' 可以匹配 "plain" 中的'p'。
[n-m]	匹配m到n之间的任意单个字符，例如[0-9],[a-z],[A-Z]
*	匹配前面的子表达式零次或多次。例如，a* 能匹配 "a" 以及 "ab"。* 等价于{0,}。
+	匹配前面的子表达式一次或多次。例如，'a+' 能匹配 "ab" 以及 "abc"，但不能匹配 "a"。+ 等价于 {1,}。
?	匹配前面的子表达式一次或多次。例如，'a?' 能匹配 "ab" 以及 "a"。? 等价于 {0,1}。
a1| a2|a3	匹配 a1 或 a2 或 a3。例如，'z|food' 能匹配 "z" 或 "food"。'(z|f)ood' 则匹配 "zood" 或 "food"。
{n}	n 是一个非负整数。匹配确定的 n 次。例如，'o{2}' 不能匹配 "Bob" 中的 'o'，但是能匹配 "food" 中的两个 o。
{n,}	匹配前面的子表达式n次到多次。例如，'o{2,}' 不仅能匹配 "food" ，也能匹配 "foood"。
{n,m}	n 和 m 均为非负整数，其中n <= m。最少匹配 n 次且最多匹配 m 次。
{,m}	匹配前面的子表达式0次到m次
(….)	元素组合，即将模式元素组成单一元素，例如（do）*意思是匹配0个多或多个do

匹配模式^

从字符串首部分进行匹配，这边匹配s开头的，匹配符合返回1，不符合返回0。应用到表中，既符合返回匹配到的数据。

 1 mysql> select 'selina' REGEXP '^s';
 2 +----------------------+
 3 | 'selina' REGEXP '^s' |
 4 +----------------------+
 5 |                    1 |
 6 +----------------------+
 7 1 row in set
 8 
 9 mysql> select 'aelina' REGEXP '^s';
10 +----------------------+
11 | 'aelina' REGEXP '^s' |
12 +----------------------+
13 |                    0 |
14 +----------------------+
15 1 row in set

 1 mysql> select * from user2;
 2 +----+--------+-----+----------+-----+
 3 | id | name   | age | address  | sex |
 4 +----+--------+-----+----------+-----+
 5 |  1 | brand  |  21 | fuzhou   |   1 |
 6 |  2 | helen  |  20 | quanzhou |   0 |
 7 |  3 | sol    |  21 | xiamen   |   0 |
 8 |  4 | weng   |  33 | guizhou  |   1 |
 9 |  5 | selina |  25 | NULL     |   0 |
10 +----+--------+-----+----------+-----+
11 5 rows in set
12 
13 mysql> select * from user2 where name REGEXP '^s';
14 +----+--------+-----+---------+-----+
15 | id | name   | age | address | sex |
16 +----+--------+-----+---------+-----+
17 |  3 | sol    |  21 | xiamen  |   0 |
18 |  5 | selina |  25 | NULL    |   0 |
19 +----+--------+-----+---------+-----+
20 2 rows in set

匹配模式$

从字符串尾部进行匹配，这边匹配名称以d结尾的数据。

 1 mysql> select * from user2;
 2 +----+--------+-----+----------+-----+
 3 | id | name   | age | address  | sex |
 4 +----+--------+-----+----------+-----+
 5 |  1 | brand  |  21 | fuzhou   |   1 |
 6 |  2 | helen  |  20 | quanzhou |   0 |
 7 |  3 | sol    |  21 | xiamen   |   0 |
 8 |  4 | weng   |  33 | guizhou  |   1 |
 9 |  5 | selina |  25 | NULL     |   0 |
10 +----+--------+-----+----------+-----+
11 5 rows in set
12 
13 mysql> select * from user2 where name REGEXP 'd$';
14 +----+-------+-----+---------+-----+
15 | id | name  | age | address | sex |
16 +----+-------+-----+---------+-----+
17 |  1 | brand |  21 | fuzhou  |   1 |
18 +----+-------+-----+---------+-----+
19 1 row in set 

匹配模式.

. 是匹配任意单个字符，下面脚本匹配 n并且后面带一个任意字符的条件

 1 mysql> select * from user2;
 2 +----+--------+-----+----------+-----+
 3 | id | name   | age | address  | sex |
 4 +----+--------+-----+----------+-----+
 5 |  1 | brand  |  21 | fuzhou   |   1 |
 6 |  2 | helen  |  20 | quanzhou |   0 |
 7 |  3 | sol    |  21 | xiamen   |   0 |
 8 |  4 | weng   |  33 | guizhou  |   1 |
 9 |  5 | selina |  25 | NULL     |   0 |
10 +----+--------+-----+----------+-----+
11 5 rows in set
12 
13 mysql> select * from user2 where name REGEXP 'n.';
14 +----+--------+-----+---------+-----+
15 | id | name   | age | address | sex |
16 +----+--------+-----+---------+-----+
17 |  1 | brand  |  21 | fuzhou  |   1 |
18 |  4 | weng   |  33 | guizhou |   1 |
19 |  5 | selina |  25 | NULL    |   0 |
20 +----+--------+-----+---------+-----+
21 3 rows in set

匹配模式[...]

指匹配括号内的任意单个字符，只要有一个字符符合条件即可。下面例子能匹配到b、w、z的 只有brand、weng 两个名称。

 1 mysql> select * from user2;
 2 +----+--------+-----+----------+-----+
 3 | id | name   | age | address  | sex |
 4 +----+--------+-----+----------+-----+
 5 |  1 | brand  |  21 | fuzhou   |   1 |
 6 |  2 | helen  |  20 | quanzhou |   0 |
 7 |  3 | sol    |  21 | xiamen   |   0 |
 8 |  4 | weng   |  33 | guizhou  |   1 |
 9 |  5 | selina |  25 | NULL     |   0 |
10 +----+--------+-----+----------+-----+
11 5 rows in set
12 
13 mysql> select * from user2 where name REGEXP [bwz];
14 1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '[bwz]' at line 1
15 mysql> select * from user2 where name REGEXP '[bwz]';
16 +----+-------+-----+---------+-----+
17 | id | name  | age | address | sex |
18 +----+-------+-----+---------+-----+
19 |  1 | brand |  21 | fuzhou  |   1 |
20 |  4 | weng  |  33 | guizhou |   1 |
21 +----+-------+-----+---------+-----+
22 2 rows in set 

匹配模式[^...] 

[^...]取反的意思，指匹配未包含的任意字符。例如， '[^brand]' 可以匹配 "helen" 中的'h'，"sol" 的 "s"，"weng" 的 "w"，"selina" 的 "s"，但无法匹配"brand"，所以被过滤了。

 1 mysql> select * from user2;
 2 +----+--------+-----+----------+-----+
 3 | id | name   | age | address  | sex |
 4 +----+--------+-----+----------+-----+
 5 |  1 | brand  |  21 | fuzhou   |   1 |
 6 |  2 | helen  |  20 | quanzhou |   0 |
 7 |  3 | sol    |  21 | xiamen   |   0 |
 8 |  4 | weng   |  33 | guizhou  |   1 |
 9 |  5 | selina |  25 | NULL     |   0 |
10 +----+--------+-----+----------+-----+
11 5 rows in set
12 
13 mysql> select * from user2 where name REGEXP '[^brand]';
14 +----+--------+-----+----------+-----+
15 | id | name   | age | address  | sex |
16 +----+--------+-----+----------+-----+
17 |  2 | helen  |  20 | quanzhou |   0 |
18 |  3 | sol    |  21 | xiamen   |   0 |
19 |  4 | weng   |  33 | guizhou  |   1 |
20 |  5 | selina |  25 | NULL     |   0 |
21 +----+--------+-----+----------+-----+
22 4 rows in set

匹配模式[n-m]

匹配m到n之间的任意单个字符，例如[0-9],[a-z],[A-Z]，下方代码中，任何元素不在a - e之间的"sol" 被过滤了。

 1 mysql> select * from user2;
 2 +----+--------+-----+----------+-----+
 3 | id | name   | age | address  | sex |
 4 +----+--------+-----+----------+-----+
 5 |  1 | brand  |  21 | fuzhou   |   1 |
 6 |  2 | helen  |  20 | quanzhou |   0 |
 7 |  3 | sol    |  21 | xiamen   |   0 |
 8 |  4 | weng   |  33 | guizhou  |   1 |
 9 |  5 | selina |  25 | NULL     |   0 |
10 +----+--------+-----+----------+-----+
11 5 rows in set
12 
13 mysql> select * from user2 where name REGEXP '[a-e]';
14 +----+--------+-----+----------+-----+
15 | id | name   | age | address  | sex |
16 +----+--------+-----+----------+-----+
17 |  1 | brand  |  21 | fuzhou   |   1 |
18 |  2 | helen  |  20 | quanzhou |   0 |
19 |  4 | weng   |  33 | guizhou  |   1 |
20 |  5 | selina |  25 | NULL     |   0 |
21 +----+--------+-----+----------+-----+
22 4 rows in set

匹配模式 *

匹配前面的子表达式零次或多次。例如，a* 能匹配 "a" 以及 "ab"。* 等价于{0,}。 下面的 "e*g" 可以匹配的只有 "weng" 这个名称。

 1 mysql> select * from user2;
 2 +----+--------+-----+----------+-----+
 3 | id | name   | age | address  | sex |
 4 +----+--------+-----+----------+-----+
 5 |  1 | brand  |  21 | fuzhou   |   1 |
 6 |  2 | helen  |  20 | quanzhou |   0 |
 7 |  3 | sol    |  21 | xiamen   |   0 |
 8 |  4 | weng   |  33 | guizhou  |   1 |
 9 |  5 | selina |  25 | NULL     |   0 |
10 +----+--------+-----+----------+-----+
11 5 rows in set
12 
13 mysql> select * from user2 where name REGEXP 'e*g';
14 +----+------+-----+---------+-----+
15 | id | name | age | address | sex |
16 +----+------+-----+---------+-----+
17 |  4 | weng |  33 | guizhou |   1 |
18 +----+------+-----+---------+-----+
19 1 row in set 

匹配模式 +

匹配前面的子表达式一次或多次。例如，'a+' 能匹配 "ab" 以及 "abc"，但不能匹配 "a"。+ 等价于 {1,}。如下方的脚本，符合条件的是1到多个的n加上一个d的组合，只有 "brand" 和 "annd" 符合。

 1 mysql> select * from user2;
 2 +----+--------+-----+----------+-----+
 3 | id | name   | age | address  | sex |
 4 +----+--------+-----+----------+-----+
 5 |  1 | brand  |  21 | fuzhou   |   1 |
 6 |  2 | helen  |  20 | quanzhou |   0 |
 7 |  3 | sol    |  21 | xiamen   |   0 |
 8 |  4 | weng   |  33 | guizhou  |   1 |
 9 |  5 | selina |  25 | NULL     |   0 |
10 |  6 | anny   |  23 | shanghai |   0 |
11 |  7 | annd   |  24 | shanghai |   1 |
12 +----+--------+-----+----------+-----+
13 7 rows in set
14 
15 mysql> select * from user2 where name REGEXP 'n+d';
16 +----+-------+-----+----------+-----+
17 | id | name  | age | address  | sex |
18 +----+-------+-----+----------+-----+
19 |  1 | brand |  21 | fuzhou   |   1 |
20 |  7 | annd  |  24 | shanghai |   1 |
21 +----+-------+-----+----------+-----+
22 2 rows in set

匹配模式 ?

匹配前面的子表达式一次或多次。例如，'a?' 能匹配 "ab" 以及 "a"。? 等价于 {0,1}。e为1个或者0个，后面再用 l 限制，所以符合的只有三个。

 1 mysql> select * from user2;
 2 +----+--------+-----+----------+-----+
 3 | id | name   | age | address  | sex |
 4 +----+--------+-----+----------+-----+
 5 |  1 | brand  |  21 | fuzhou   |   1 |
 6 |  2 | helen  |  20 | quanzhou |   0 |
 7 |  3 | sol    |  21 | xiamen   |   0 |
 8 |  4 | weng   |  33 | guizhou  |   1 |
 9 |  5 | selina |  25 | NULL     |   0 |
10 |  6 | anny   |  23 | shanghai |   0 |
11 |  7 | annd   |  24 | shanghai |   1 |
12 +----+--------+-----+----------+-----+
13 7 rows in set
14 
15 mysql> select * from user2 where name REGEXP 'e?l';
16 +----+--------+-----+----------+-----+
17 | id | name   | age | address  | sex |
18 +----+--------+-----+----------+-----+
19 |  2 | helen  |  20 | quanzhou |   0 |
20 |  3 | sol    |  21 | xiamen   |   0 |
21 |  5 | selina |  25 | NULL     |   0 |
22 +----+--------+-----+----------+-----+
23 3 rows in set 

匹配模式 a1| a2|a3

匹配 a1 或 a2 或 a3。例如下方，'nn|en' 能分别匹配到 "anny" 、"annd" 和 "helen"、"weng"。

 1 mysql> select * from user2;
 2 +----+--------+-----+----------+-----+
 3 | id | name   | age | address  | sex |
 4 +----+--------+-----+----------+-----+
 5 |  1 | brand  |  21 | fuzhou   |   1 |
 6 |  2 | helen  |  20 | quanzhou |   0 |
 7 |  3 | sol    |  21 | xiamen   |   0 |
 8 |  4 | weng   |  33 | guizhou  |   1 |
 9 |  5 | selina |  25 | NULL     |   0 |
10 |  6 | anny   |  23 | shanghai |   0 |
11 |  7 | annd   |  24 | shanghai |   1 |
12 +----+--------+-----+----------+-----+
13 7 rows in set
14 
15 mysql> select * from user2 where name REGEXP 'nn|en';
16 +----+-------+-----+----------+-----+
17 | id | name  | age | address  | sex |
18 +----+-------+-----+----------+-----+
19 |  2 | helen |  20 | quanzhou |   0 |
20 |  4 | weng  |  33 | guizhou  |   1 |
21 |  6 | anny  |  23 | shanghai |   0 |
22 |  7 | annd  |  24 | shanghai |   1 |
23 +----+-------+-----+----------+-----+
24 4 rows in set

匹配模式 {n} {n,} {n,m} {,m} 

 n 和 m 均为非负整数，其中n <= m。最少匹配 n 次且最多匹配 m 次。m为空代表>=n的任意数，n为空代表0。

 1 mysql> select * from user2;
 2 +----+--------+-----+----------+-----+
 3 | id | name   | age | address  | sex |
 4 +----+--------+-----+----------+-----+
 5 |  1 | brand  |  21 | fuzhou   |   1 |
 6 |  2 | helen  |  20 | quanzhou |   0 |
 7 |  3 | sol    |  21 | xiamen   |   0 |
 8 |  4 | weng   |  33 | guizhou  |   1 |
 9 |  5 | selina |  25 | NULL     |   0 |
10 |  6 | anny   |  23 | shanghai |   0 |
11 |  7 | annd   |  24 | shanghai |   1 |
12 +----+--------+-----+----------+-----+
13 7 rows in set
14 
15 mysql> select * from user2 where name REGEXP 'n{2}';
16 +----+------+-----+----------+-----+
17 | id | name | age | address  | sex |
18 +----+------+-----+----------+-----+
19 |  6 | anny |  23 | shanghai |   0 |
20 |  7 | annd |  24 | shanghai |   1 |
21 +----+------+-----+----------+-----+
22 2 rows in set
23 
24 mysql> select * from user2 where name REGEXP 'n{1,2}';
25 +----+--------+-----+----------+-----+
26 | id | name   | age | address  | sex |
27 +----+--------+-----+----------+-----+
28 |  1 | brand  |  21 | fuzhou   |   1 |
29 |  2 | helen  |  20 | quanzhou |   0 |
30 |  4 | weng   |  33 | guizhou  |   1 |
31 |  5 | selina |  25 | NULL     |   0 |
32 |  6 | anny   |  23 | shanghai |   0 |
33 |  7 | annd   |  24 | shanghai |   1 |
34 +----+--------+-----+----------+-----+
35 6 rows in set
36 
37 mysql> select * from user2 where name REGEXP 'l{1,}';
38 +----+--------+-----+----------+-----+
39 | id | name   | age | address  | sex |
40 +----+--------+-----+----------+-----+
41 |  2 | helen  |  20 | quanzhou |   0 |
42 |  3 | sol    |  21 | xiamen   |   0 |
43 |  5 | selina |  25 | NULL     |   0 |
44 +----+--------+-----+----------+-----+
45 3 rows in set

匹配模式(...) 

假设括号内容为abc，则是将abc作为一个整体去匹配，符合这个规则的数据被过滤出来。下面以an为例子，配合上面学过的知识。

 1 mysql> select * from user2;
 2 +----+--------+-----+----------+-----+
 3 | id | name   | age | address  | sex |
 4 +----+--------+-----+----------+-----+
 5 |  1 | brand  |  21 | fuzhou   |   1 |
 6 |  2 | helen  |  20 | quanzhou |   0 |
 7 |  3 | sol    |  21 | xiamen   |   0 |
 8 |  4 | weng   |  33 | guizhou  |   1 |
 9 |  5 | selina |  25 | NULL     |   0 |
10 |  6 | anny   |  23 | shanghai |   0 |
11 |  7 | annd   |  24 | shanghai |   1 |
12 +----+--------+-----+----------+-----+
13 7 rows in set
14 
15 mysql> select * from user2 where name REGEXP '(an)+';
16 +----+-------+-----+----------+-----+
17 | id | name  | age | address  | sex |
18 +----+-------+-----+----------+-----+
19 |  1 | brand |  21 | fuzhou   |   1 |
20 |  6 | anny  |  23 | shanghai |   0 |
21 |  7 | annd  |  24 | shanghai |   1 |
22 +----+-------+-----+----------+-----+
23 3 rows in set
24 
25 mysql> select * from user2 where name REGEXP '(ann)+';
26 +----+------+-----+----------+-----+
27 | id | name | age | address  | sex |
28 +----+------+-----+----------+-----+
29 |  6 | anny |  23 | shanghai |   0 |
30 |  7 | annd |  24 | shanghai |   1 |
31 +----+------+-----+----------+-----+
32 2 rows in set
33 
34 mysql> select * from user2 where name REGEXP '(an).*d{1,2}';
35 +----+-------+-----+----------+-----+
36 | id | name  | age | address  | sex |
37 +----+-------+-----+----------+-----+
38 |  1 | brand |  21 | fuzhou   |   1 |
39 |  7 | annd  |  24 | shanghai |   1 |
40 +----+-------+-----+----------+-----+
41 2 rows in set

匹配特殊字符 \

正则表达式语言由具有特定含义的特殊字符构成。我们已经看到.、 []、|、*、+ 等， 那我们是怎么匹配这些字符的。如下示例，我们使用 \ 来匹配特殊字符，\为前导， \-表示查找-， \.表示查找.。

 1 mysql> select * from user3;
 2 +----+------+-------+
 3 | id | age  | name  |
 4 +----+------+-------+
 5 |  1 |   20 | brand |
 6 |  2 |   22 | sol   |
 7 |  3 |   20 | helen |
 8 |  4 | 19.5 | diny  |
 9 +----+------+-------+
10 4 rows in set
11 
12 mysql> select * from user3 where age REGEXP '[0-9]+\.[0-9]+';
13 +----+------+------+
14 | id | age  | name |
15 +----+------+------+
16 |  4 | 19.5 | diny |
17 +----+------+------+
18 1 row in set 

总结

1.当我们需要用正则匹配数据的时候，可以使用REGEXP和NOT REGEXP操作符(类似LIKE和NOT LIKE)；

2.REGEXP默认不区分大小写，可以使用BINARY关键词强制区分大小写； WHERE NAME REGEXP BINARY ‘^[A-Z]’;

3.REGEXP默认是部分匹配原则，即有一个匹配上则返回真。例如：SELECT  'A123' REGEXP BINARY '[A-Z]'，返回的是1;

4、如果使用 () 进行匹配，则是将括号内部的内容当作整体去匹配，比如 (ABC)，则需要匹配整个ABC。

5、这边只是看介绍了正则的基础知识，想要更为透彻的了解可以参考 正则教程 ，我觉得写的不错。