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MySQL全面瓦解8：查询的正则匹配
爱新觉羅丶高
发布于 2022-8-1 18:52
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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^
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。
mysql> select 'selina' REGEXP '^s';
+----------------------+
| 'selina' REGEXP '^s' |
+----------------------+
| 1 |
+----------------------+
1 row in set
mysql> select 'aelina' REGEXP '^s';
+----------------------+
| 'aelina' REGEXP '^s' |
+----------------------+
| 0 |
+----------------------+
1 row in setmysql> select * from user2;
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 2 | helen | 20 | quanzhou | 0 |
| 3 | sol | 21 | xiamen | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
+----+--------+-----+----------+-----+
5 rows in set
mysql> select * from user2 where name REGEXP '^s';
+----+--------+-----+---------+-----+
| id | name | age | address | sex |
+----+--------+-----+---------+-----+
| 3 | sol | 21 | xiamen | 0 |
| 5 | selina | 25 | NULL | 0 |
+----+--------+-----+---------+-----+
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。
mysql> select * from user2;
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 2 | helen | 20 | quanzhou | 0 |
| 3 | sol | 21 | xiamen | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
+----+--------+-----+----------+-----+
5 rows in set
mysql> select * from user2 where name REGEXP 'd$';
+----+-------+-----+---------+-----+
| id | name | age | address | sex |
+----+-------+-----+---------+-----+
| 1 | brand | 21 | fuzhou | 1 |
+----+-------+-----+---------+-----+
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
mysql> select * from user2;
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 2 | helen | 20 | quanzhou | 0 |
| 3 | sol | 21 | xiamen | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
+----+--------+-----+----------+-----+
5 rows in set
mysql> select * from user2 where name REGEXP 'n.';
+----+--------+-----+---------+-----+
| id | name | age | address | sex |
+----+--------+-----+---------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
+----+--------+-----+---------+-----+
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。
mysql> select * from user2;
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 2 | helen | 20 | quanzhou | 0 |
| 3 | sol | 21 | xiamen | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
+----+--------+-----+----------+-----+
5 rows in set
mysql> select * from user2 where name REGEXP [bwz];
1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL rver version for the right syntax to use near '[bwz]' at line 1
mysql> select * from user2 where name REGEXP '[bwz]';
+----+-------+-----+---------+-----+
| id | name | age | address | sex |
+----+-------+-----+---------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 4 | weng | 33 | guizhou | 1 |
+----+-------+-----+---------+-----+
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。
mysql> select * from user2;
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 2 | helen | 20 | quanzhou | 0 |
| 3 | sol | 21 | xiamen | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
+----+--------+-----+----------+-----+
5 rows in set
mysql> select * from user2 where name REGEXP '[^brand]';
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 2 | helen | 20 | quanzhou | 0 |
| 3 | sol | 21 | xiamen | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
+----+--------+-----+----------+-----+
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。
mysql> select * from user2;
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 2 | helen | 20 | quanzhou | 0 |
| 3 | sol | 21 | xiamen | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
+----+--------+-----+----------+-----+
5 rows in set
mysql> select * from user2 where name REGEXP '[a-e]';
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 2 | helen | 20 | quanzhou | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
+----+--------+-----+----------+-----+
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。
mysql> select * from user2;
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 2 | helen | 20 | quanzhou | 0 |
| 3 | sol | 21 | xiamen | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
+----+--------+-----+----------+-----+
5 rows in set
mysql> select * from user2 where name REGEXP 'e*g';
+----+------+-----+---------+-----+
| id | name | age | address | sex |
+----+------+-----+---------+-----+
| 4 | weng | 33 | guizhou | 1 |
+----+------+-----+---------+-----+
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。
mysql> select * from user2;
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 2 | helen | 20 | quanzhou | 0 |
| 3 | sol | 21 | xiamen | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
| 6 | anny | 23 | shanghai | 0 |
| 7 | annd | 24 | shanghai | 1 |
+----+--------+-----+----------+-----+
7 rows in set
mysql> select * from user2 where name REGEXP 'n+d';
+----+-------+-----+----------+-----+
| id | name | age | address | sex |
+----+-------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 7 | annd | 24 | shanghai | 1 |
+----+-------+-----+----------+-----+
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。
mysql> select * from user2;
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 2 | helen | 20 | quanzhou | 0 |
| 3 | sol | 21 | xiamen | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
| 6 | anny | 23 | shanghai | 0 |
| 7 | annd | 24 | shanghai | 1 |
+----+--------+-----+----------+-----+
7 rows in set
mysql> select * from user2 where name REGEXP 'e?l';
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 2 | helen | 20 | quanzhou | 0 |
| 3 | sol | 21 | xiamen | 0 |
| 5 | selina | 25 | NULL | 0 |
+----+--------+-----+----------+-----+
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"。
mysql> select * from user2;
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 2 | helen | 20 | quanzhou | 0 |
| 3 | sol | 21 | xiamen | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
| 6 | anny | 23 | shanghai | 0 |
| 7 | annd | 24 | shanghai | 1 |
+----+--------+-----+----------+-----+
7 rows in set
mysql> select * from user2 where name REGEXP 'nn|en';
+----+-------+-----+----------+-----+
| id | name | age | address | sex |
+----+-------+-----+----------+-----+
| 2 | helen | 20 | quanzhou | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 6 | anny | 23 | shanghai | 0 |
| 7 | annd | 24 | shanghai | 1 |
+----+-------+-----+----------+-----+
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。
mysql> select * from user2;
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 2 | helen | 20 | quanzhou | 0 |
| 3 | sol | 21 | xiamen | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
| 6 | anny | 23 | shanghai | 0 |
| 7 | annd | 24 | shanghai | 1 |
+----+--------+-----+----------+-----+
7 rows in set
mysql> select * from user2 where name REGEXP 'n{2}';
+----+------+-----+----------+-----+
| id | name | age | address | sex |
+----+------+-----+----------+-----+
| 6 | anny | 23 | shanghai | 0 |
| 7 | annd | 24 | shanghai | 1 |
+----+------+-----+----------+-----+
2 rows in set
mysql> select * from user2 where name REGEXP 'n{1,2}';
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 2 | helen | 20 | quanzhou | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
| 6 | anny | 23 | shanghai | 0 |
| 7 | annd | 24 | shanghai | 1 |
+----+--------+-----+----------+-----+
6 rows in set
mysql> select * from user2 where name REGEXP 'l{1,}';
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 2 | helen | 20 | quanzhou | 0 |
| 3 | sol | 21 | xiamen | 0 |
| 5 | selina | 25 | NULL | 0 |
+----+--------+-----+----------+-----+
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。
mysql> select * from user2;
+----+--------+-----+----------+-----+
| id | name | age | address | sex |
+----+--------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 2 | helen | 20 | quanzhou | 0 |
| 3 | sol | 21 | xiamen | 0 |
| 4 | weng | 33 | guizhou | 1 |
| 5 | selina | 25 | NULL | 0 |
| 6 | anny | 23 | shanghai | 0 |
| 7 | annd | 24 | shanghai | 1 |
+----+--------+-----+----------+-----+
7 rows in set
mysql> select * from user2 where name REGEXP '(an)+';
+----+-------+-----+----------+-----+
| id | name | age | address | sex |
+----+-------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 6 | anny | 23 | shanghai | 0 |
| 7 | annd | 24 | shanghai | 1 |
+----+-------+-----+----------+-----+
3 rows in set
mysql> select * from user2 where name REGEXP '(ann)+';
+----+------+-----+----------+-----+
| id | name | age | address | sex |
+----+------+-----+----------+-----+
| 6 | anny | 23 | shanghai | 0 |
| 7 | annd | 24 | shanghai | 1 |
+----+------+-----+----------+-----+
2 rows in set
mysql> select * from user2 where name REGEXP '(an).*d{1,2}';
+----+-------+-----+----------+-----+
| id | name | age | address | sex |
+----+-------+-----+----------+-----+
| 1 | brand | 21 | fuzhou | 1 |
| 7 | annd | 24 | shanghai | 1 |
+----+-------+-----+----------+-----+
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.。
mysql> select * from user3;
+----+------+-------+
| id | age | name |
+----+------+-------+
| 1 | 20 | brand |
| 2 | 22 | sol |
| 3 | 20 | helen |
| 4 | 19.5 | diny |
+----+------+-------+
4 rows in set
mysql> select * from user3 where age REGEXP '[0-9]+\\.[0-9]+';
+----+------+------+
| id | age | name |
+----+------+------+
| 4 | 19.5 | diny |
+----+------+------+
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。
文章转载自公众号：架构与思维
已于2022-8-1 18:52:38修改
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