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MySQL 正则表达式

2016-04-06 21:05:50  来源:极客头条
  正则表达式用来描述或者匹配符合规则的字符串。它的用法和like比较相似,但是它又比like更强大,能够实现一些很特殊的规则匹配;正则表达式需要使用REGEXP命令,匹配上返回"1"匹配不上返回"0",REGEXP相当于like '%%'。
  在字符的开启处进行匹配
  在字符的末尾处进行匹配
  匹配任何字符(包括回车和新行)
  [….]
  匹配括号内的任意单个字符
  [m-n]
  匹配m到n之间的任意单个字符,例如[0-9],[a-z],[A-Z]
  [^..]
  不能匹配括号内的任意单个字符
  匹配0个或多个a,包括空
  匹配一个或多个a,不包括空
  匹配一个或0个a
  a1| a2
  匹配a1或a2
  a{m}
  匹配m个a
  a{m,}
  匹配m个或者更多个a
  a{m,n}
  匹配m到n个a
  a{,n}
  匹配0到n个a
  (….)
  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
  在字符串开始处进行匹配
mysql> SELECT 'abc' REGEXP '^a'; +-------------------+ | 'abc' REGEXP '^a' | +-------------------+ | 1 | +-------------------+ 1 row in set (0.00 sec)   在字符串末尾开始匹配
mysql> SELECT 'abc' REGEXP 'a$'; +-------------------+ | 'abc' REGEXP 'a$' | +-------------------+ | 0 | +-------------------+ 1 row in set (0.01 sec) mysql> SELECT 'abc' REGEXP 'c$'; +-------------------+ | 'abc' REGEXP 'c$' | +-------------------+ | 1 | +-------------------+ 1 row in set (0.00 sec)   匹配任意字符
mysql> SELECT 'abc' REGEXP '.a'; +-------------------+ | 'abc' REGEXP '.a' | +-------------------+ | 0 | +-------------------+ 1 row in set (0.00 sec) mysql> SELECT 'abc' REGEXP '.b'; +-------------------+ | 'abc' REGEXP '.b' | +-------------------+ | 1 | +-------------------+ 1 row in set (0.00 sec) mysql> SELECT 'abc' REGEXP '.c'; +-------------------+ | 'abc' REGEXP '.c' | +-------------------+ | 1 | +-------------------+ 1 row in set (0.00 sec) mysql> SELECT 'abc' REGEXP 'a.'; +-------------------+ | 'abc' REGEXP 'a.' | +-------------------+ | 1 | +-------------------+ 1 row in set (0.00 sec)   [...]
  匹配括号内的任意单个字符
mysql> SELECT 'abc' REGEXP '[xyz]'; +----------------------+ | 'abc' REGEXP '[xyz]' | +----------------------+ | 0 | +----------------------+ 1 row in set (0.00 sec) mysql> SELECT 'abc' REGEXP '[xaz]'; +----------------------+ | 'abc' REGEXP '[xaz]' | +----------------------+ | 1 | +----------------------+ 1 row in set (0.00 sec)   [^...]:注意^符合只有在[]内才是取反的意思,在别的地方都是表示开始处匹配
   匹配不出括号没的任意个字符,注意:REGEXP 前的匹配字符作为一个整体
mysql> SELECT 'a' REGEXP '[^abc]'; +---------------------+ | 'a' REGEXP '[^abc]' | +---------------------+ | 0 | +---------------------+ 1 row in set (0.00 sec) mysql> SELECT 'x' REGEXP '[^abc]'; +---------------------+ | 'x' REGEXP '[^abc]' | +---------------------+ | 1 | +---------------------+ 1 row in set (0.00 sec) mysql> SELECT 'abc' REGEXP '[^a]'; +---------------------+ | 'abc' REGEXP '[^a]' | +---------------------+ | 1 | +---------------------+ 1 row in set (0.00 sec)   'abc'作为一个整体,所以它匹配不了a
  匹配0个或多个a,包括空字符串。
  mysql> SELECT 'stab' REGEXP '.ta*b';
+-----------------------+
| 'stab' REGEXP '.ta*b' |
+-----------------------+
| 1 |
+-----------------------+
1 row in set (0.00 sec)
  mysql> SELECT 'stb' REGEXP '.ta*b';
+----------------------+
| 'stb' REGEXP '.ta*b' |
+----------------------+
| 1 |
+----------------------+
1 row in set (0.00 sec)
mysql> SELECT '' REGEXP 'a*'; +----------------+ | '' REGEXP 'a*' | +----------------+ | 1 | +----------------+ 1 row in set (0.00 sec)   匹配1个或者多个a,但是不包括空字符
mysql> SELECT 'stab' REGEXP '.ta+b'; +-----------------------+ | 'stab' REGEXP '.ta+b' | +-----------------------+ | 1 | +-----------------------+ 1 row in set (0.00 sec) mysql> SELECT 'stb' REGEXP '.ta+b'; +----------------------+ | 'stb' REGEXP '.ta+b' | +----------------------+ | 0 | +----------------------+ 1 row in set (0.00 sec)   匹配0个或者1个a
mysql> SELECT 'stb' REGEXP '.ta?b'; +----------------------+ | 'stb' REGEXP '.ta?b' | +----------------------+ | 1 | +----------------------+ 1 row in set (0.00 sec) mysql> SELECT 'stab' REGEXP '.ta?b'; +-----------------------+ | 'stab' REGEXP '.ta?b' | +-----------------------+ | 1 | +-----------------------+ 1 row in set (0.00 sec) mysql> SELECT 'staab' REGEXP '.ta?b'; +------------------------+ | 'staab' REGEXP '.ta?b' | +------------------------+ | 0 | +------------------------+ 1 row in set (0.00 sec)   a1|a2
  匹配a1或者a2,
mysql> SELECT 'a' REGEXP 'a|b'; +------------------+ | 'a' REGEXP 'a|b' | +------------------+ | 1 | +------------------+ 1 row in set (0.00 sec) mysql> SELECT 'b' REGEXP 'a|b'; +------------------+ | 'b' REGEXP 'a|b' | +------------------+ | 1 | +------------------+ 1 row in set (0.00 sec) mysql> SELECT 'b' REGEXP '^(a|b)'; +---------------------+ | 'b' REGEXP '^(a|b)' | +---------------------+ | 1 | +---------------------+ 1 row in set (0.00 sec) mysql> SELECT 'a' REGEXP '^(a|b)'; +---------------------+ | 'a' REGEXP '^(a|b)' | +---------------------+ | 1 | +---------------------+ 1 row in set (0.00 sec) mysql> SELECT 'c' REGEXP '^(a|b)'; +---------------------+ | 'c' REGEXP '^(a|b)' | +---------------------+ | 0 | +---------------------+ 1 row in set (0.00 sec)   注意:^符合只有在[]内才是取反的意思,在别的地方都是表示开始处匹配
  a{m}
  匹配m个a
mysql> SELECT 'auuuuc' REGEXP 'au{4}c'; +--------------------------+ | 'auuuuc' REGEXP 'au{4}c' | +--------------------------+ | 1 | +--------------------------+ 1 row in set (0.00 sec) mysql> SELECT 'auuuuc' REGEXP 'au{3}c'; +--------------------------+ | 'auuuuc' REGEXP 'au{3}c' | +--------------------------+ | 0 | +--------------------------+ 1 row in set (0.00 sec)   a{m,}
  匹配m个或者更多个a
mysql> SELECT 'auuuuc' REGEXP 'au{3,}c'; +---------------------------+ | 'auuuuc' REGEXP 'au{3,}c' | +---------------------------+ | 1 | +---------------------------+ 1 row in set (0.00 sec) mysql> SELECT 'auuuuc' REGEXP 'au{4,}c'; +---------------------------+ | 'auuuuc' REGEXP 'au{4,}c' | +---------------------------+ | 1 | +---------------------------+ 1 row in set (0.00 sec) mysql> SELECT 'auuuuc' REGEXP 'au{5,}c'; +---------------------------+ | 'auuuuc' REGEXP 'au{5,}c' | +---------------------------+ | 0 | +---------------------------+ 1 row in set (0.00 sec)   a{m,n}
  匹配m到n个a,包含m和n
mysql> SELECT 'auuuuc' REGEXP 'au{3,5}c'; +----------------------------+ | 'auuuuc' REGEXP 'au{3,5}c' | +----------------------------+ | 1 | +----------------------------+ 1 row in set (0.00 sec) mysql> SELECT 'auuuuc' REGEXP 'au{4,5}c'; +----------------------------+ | 'auuuuc' REGEXP 'au{4,5}c' | +----------------------------+ | 1 | +----------------------------+ 1 row in set (0.00 sec) mysql> SELECT 'auuuuc' REGEXP 'au{5,10}c'; +-----------------------------+ | 'auuuuc' REGEXP 'au{5,10}c' | +-----------------------------+ | 0 | +-----------------------------+ 1 row in set (0.00 sec)   a{,n}
  这个暂时还没有测出来,意思应该不是匹配0到n个a,如果是表达0到n个a也可以用{0,n}代替
  (abc)
  将abc作为一个序列匹配,不用括号括起来都是用单个字符去匹配,如果要把多个字符作为一个整体去匹配就需要用到括号,所以括号适合上面的所有情况。
mysql> SELECT 'xababy' REGEXP 'x(abab)y'; +----------------------------+ | 'xababy' REGEXP 'x(abab)y' | +----------------------------+ | 1 | +----------------------------+ 1 row in set (0.00 sec) mysql> SELECT 'xababy' REGEXP 'x(ab)*y'; +---------------------------+ | 'xababy' REGEXP 'x(ab)*y' | +---------------------------+ | 1 | +---------------------------+ 1 row in set (0.00 sec) mysql> SELECT 'xababy' REGEXP 'x(ab){1,2}y'; +-------------------------------+ | 'xababy' REGEXP 'x(ab){1,2}y' | +-------------------------------+ | 1 | +-------------------------------+ 1 row in set (0.00 sec)    特别要注意最后的()的命令,如果不使用()那么所有的都是指单个字符去做匹配,如果需要使用多个字符作为一个整体去匹配就需要将多个字符使用()给括起来