MySQL模糊查询

1. 模糊查询

模糊查询是模式匹配的一种，MySQL中有两种模糊查询方式：

1. 标准SQL模式匹配（关键字LIKE）
2. 扩展正则表达式（关键字REGEXP/RLIKE）

2. 标准SQL模式匹配

_    匹配任意单字符
%    匹配任意多个字符

 标准SQL模式匹配使用关键字LIKE，默认不区分大小写

3. 扩展正则表达式

.     
匹配任意单字符
[...] 
匹配方括号（集合）里面的任意单字符，比如[abc]匹配a,b或者c;[a-z]匹配任意单字母;[0-9]匹配任意单数字
*    
匹配零个或者多个它前面的实例，比如x*匹配任意数量的x;[0-9]*匹配任意数量的数字;.*匹配任意数量的任何实例

扩展正则表达式使用关键字REGEXP/RLIKE，以^开始，以$结束

默认不区分大小写，使用关键字BINARY强制区分大小写

4. 查询举例

1. 找到name以'b'开始的记录

mysql> SELECT * FROM PET WHERE name LIKE 'b%';
+--------+--------+---------+------+------------+------------+
| name   | owner  | species | sex  | birth      | death      |
+--------+--------+---------+------+------------+------------+
| Buffy  | Harold | dog     | f    | 1989-05-13 | NULL       |
| Bowser | Diane  | dog     | m    | 1979-08-31 | 1995-07-29 |
+--------+--------+---------+------+------------+------------+
2 rows in set (0.01 sec)

mysql> SELECT * FROM PET WHERE name REGEXP '^b';
+--------+--------+---------+------+------------+------------+
| name   | owner  | species | sex  | birth      | death      |
+--------+--------+---------+------+------------+------------+
| Buffy  | Harold | dog     | f    | 1989-05-13 | NULL       |
| Bowser | Diane  | dog     | m    | 1979-08-31 | 1995-07-29 |
+--------+--------+---------+------+------------+------------+
2 rows in set (0.00 sec)

mysql> SELECT * FROM PET WHERE name REGEXP BINARY '^b';
Empty set (0.01 sec)

2. 找到name以'fy'结束的记录

mysql> SELECT * FROM PET WHERE name LIKE '%fy';
+--------+--------+---------+------+------------+-------+
| name   | owner  | species | sex  | birth      | death |
+--------+--------+---------+------+------------+-------+
| Fluffy | Harold | cat     | f    | 1993-02-04 | NULL  |
| Buffy  | Harold | dog     | f    | 1989-05-13 | NULL  |
+--------+--------+---------+------+------------+-------+
2 rows in set (0.00 sec)

mysql> SELECT * FROM PET WHERE name REGEXP 'fy$';
+--------+--------+---------+------+------------+-------+
| name   | owner  | species | sex  | birth      | death |
+--------+--------+---------+------+------------+-------+
| Fluffy | Harold | cat     | f    | 1993-02-04 | NULL  |
| Buffy  | Harold | dog     | f    | 1989-05-13 | NULL  |
+--------+--------+---------+------+------------+-------+
2 rows in set (0.00 sec)

3. 找到name包含'w'的记录

mysql> SELECT * FROM PET WHERE name LIKE '%w%';
+----------+-------+---------+------+------------+------------+
| name     | owner | species | sex  | birth      | death      |
+----------+-------+---------+------+------------+------------+
| Claws    | Gwen  | cat     | m    | 1994-03-17 | NULL       |
| Whistler | Gwen  | bird    | NULL | 1997-12-09 | NULL       |
| Bowser   | Diane | dog     | m    | 1979-08-31 | 1995-07-29 |
+----------+-------+---------+------+------------+------------+
3 rows in set (0.00 sec)

mysql> SELECT * FROM PET WHERE name REGEXP '.w';
+--------+-------+---------+------+------------+------------+
| name   | owner | species | sex  | birth      | death      |
+--------+-------+---------+------+------------+------------+
| Claws  | Gwen  | cat     | m    | 1994-03-17 | NULL       |
| Bowser | Diane | dog     | m    | 1979-08-31 | 1995-07-29 |
+--------+-------+---------+------+------------+------------+
2 rows in set (0.00 sec)

mysql> SELECT * FROM PET WHERE name REGEXP 'w';
+----------+-------+---------+------+------------+------------+
| name     | owner | species | sex  | birth      | death      |
+----------+-------+---------+------+------------+------------+
| Claws    | Gwen  | cat     | m    | 1994-03-17 | NULL       |
| Whistler | Gwen  | bird    | NULL | 1997-12-09 | NULL       |
| Bowser   | Diane | dog     | m    | 1979-08-31 | 1995-07-29 |
+----------+-------+---------+------+------------+------------+
3 rows in set (0.00 sec)

4. 找到name由5个字符组成且第4个字符为w的记录

mysql> SELECT * FROM PET WHERE name LIKE '___W_';
+-------+-------+---------+------+------------+-------+
| name  | owner | species | sex  | birth      | death |
+-------+-------+---------+------+------------+-------+
| Claws | Gwen  | cat     | m    | 1994-03-17 | NULL  |
+-------+-------+---------+------+------------+-------+
1 row in set (0.00 sec)

mysql> SELECT * FROM PET WHERE name REGEXP '^...w.$';
+-------+-------+---------+------+------------+-------+
| name  | owner | species | sex  | birth      | death |
+-------+-------+---------+------+------------+-------+
| Claws | Gwen  | cat     | m    | 1994-03-17 | NULL  |
+-------+-------+---------+------+------------+-------+
1 row in set (0.00 sec)

-- You could also write the previous query using the {n} (“repeat-n-times”) operator
mysql> SELECT * FROM PET WHERE name REGEXP '^.{3}w.$';
+-------+-------+---------+------+------------+-------+
| name  | owner | species | sex  | birth      | death |
+-------+-------+---------+------+------------+-------+
| Claws | Gwen  | cat     | m    | 1994-03-17 | NULL  |
+-------+-------+---------+------+------------+-------+
1 row in set (0.00 sec)

注：有时候使用NOT REGEXP更简单

更多正则表达式语法，点我直达。