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MySQL全面瓦解之查詢的正則匹配詳解

概述

上一章查詢的過濾條件，我們了解了MySQL可以通過 like % 通配符來進行模糊匹配。同樣的，它也支持其他正則表達式的匹配，我們在MySQL中使用 REGEXP 操作符來進行正則表達式匹配。用法和like相

似，但又強大很多，能夠實現一些很特殊的、復雜的規則匹配。正則表達式使用REGEXP命令進行匹配時，如果符合返回1，不符合返回0。如果默認不加任何匹配規則REGEXP相當于like '%%'。在前面加上NOT（NOT REGEXP）相當于NOT LIKE。

匹配模式分析

下面有個表格，羅列了可應用于 REGEXP 操作符中正則匹配模式，描述相對比較詳細了，后面我們一個一個來測試。

匹配模式	描述
^	匹配輸入字符串的開始位置。如果設置了 REGEXP 對象的 Multiline 屬性，^ 也匹配 '\n' 或 '\r' 之后的位置。
$	匹配輸入字符串的結束位置。如果設置了REGEXP 對象的 Multiline 屬性，$ 也匹配 '\n' 或 '\r' 之前的位置。
.	匹配除 "\n" 之外的任何單個字符。要匹配包括 '\n' 在內的任何字符，請使用 '[.\n]' 的模式。
[….]	字符集合。匹配所包含的任意一個字符。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之間的任意單個字符，例如[0-9],[a-z],[A-Z]
*	匹配前面的子表達式零次或多次。例如，a* 能匹配 "a" 以及 "ab"。* 等價于{0,}。
+	匹配前面的子表達式一次或多次。例如，'a+' 能匹配 "ab" 以及 "abc"，但不能匹配 "a"。+ 等價于 {1,}。
?	匹配前面的子表達式一次或多次。例如，'a?' 能匹配 "ab" 以及 "a"。? 等價于 {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' 則匹配 "zood" 或 "food"。
{n}	n 是一個非負整數。匹配確定的 n 次。例如，'o{2}' 不能匹配 "Bob" 中的 'o'，但是能匹配 "food" 中的兩個 o。
{n,}	匹配前面的子表達式n次到多次。例如，'o{2,}' 不僅能匹配 "food" ，也能匹配 "foood"。
{n,m}	n 和 m 均為非負整數，其中n = m。最少匹配 n 次且最多匹配 m 次。
{,m}	匹配前面的子表達式0次到m次
(….)	元素組合，即將模式元素組成單一元素，例如（do）*意思是匹配0個多或多個do

匹配模式^

從字符串首部分進行匹配，這邊匹配s開頭的，匹配符合返回1，不符合返回0。應用到表中，既符合返回匹配到的數據。

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 set

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 '^s';
+----+--------+-----+---------+-----+
| id | name | age | address | sex |
+----+--------+-----+---------+-----+
| 3 | sol | 21 | xiamen | 0 |
| 5 | selina | 25 | NULL | 0 |
+----+--------+-----+---------+-----+
2 rows in set

匹配模式$

從字符串尾部進行匹配，這邊匹配名稱以d結尾的數據。

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.

. 是匹配任意單個字符，下面腳本匹配 n并且后面帶一個任意字符的條件

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[...]

指匹配括號內的任意單個字符，只要有一個字符符合條件即可。下面例子能匹配到b、w、z的只有brand、weng 兩個名稱。

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 server 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"，但無法匹配"brand"，所以被過濾了。

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之間的任意單個字符，例如[0-9],[a-z],[A-Z]，下方代碼中，任何元素不在a - e之間的"sol" 被過濾了。

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 *

匹配前面的子表達式零次或多次。例如，a* 能匹配 "a" 以及 "ab"。* 等價于{0,}。下面的 "e*g" 可以匹配的只有 "weng" 這個名稱。

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 +

匹配前面的子表達式一次或多次。例如，'a+' 能匹配 "ab" 以及 "abc"，但不能匹配 "a"。+ 等價于 {1,}。如下方的腳本，符合條件的是1到多個的n加上一個d的組合，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 ?

匹配前面的子表達式一次或多次。例如，'a?' 能匹配 "ab" 以及 "a"。? 等價于 {0,1}。e為1個或者0個，后面再用 l 限制，所以符合的只有三個。

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' 能分別匹配到 "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 均為非負整數，其中n = m。最少匹配 n 次且最多匹配 m 次。m為空代表>=n的任意數，n為空代表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(...)

假設括號內容為abc，則是將abc作為一個整體去匹配，符合這個規則的數據被過濾出來。下面以an為例子，配合上面學過的知識。

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 \\

正則表達式語言由具有特定含義的特殊字符構成。我們已經看到.、 []、|、*、+ 等，那我們是怎么匹配這些字符的。如下示例，我們使用 \\ 來匹配特殊字符，\\為前導， \\-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

總結

1.當我們需要用正則匹配數據的時候，可以使用REGEXP和NOT REGEXP操作符(類似LIKE和NOT LIKE)；

2.REGEXP默認不區分大小寫，可以使用BINARY關鍵詞強制區分大小寫； WHERE NAME REGEXP BINARY ‘^[A-Z]';

3.REGEXP默認是部分匹配原則，即有一個匹配上則返回真。例如：SELECT 'A123' REGEXP BINARY '[A-Z]'，返回的是1;

4、如果使用 () 進行匹配，則是將括號內部的內容當作整體去匹配，比如 (ABC)，則需要匹配整個ABC。

5、這邊只是看介紹了正則的基礎知識，想要更為透徹的了解可以參考正則教程，我覺得寫的不錯。

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