Oracle正则表达式

参考网址:http://www.oradev.com/regular_expressions_sql_oracle.jsp

Metacharacters	Meaning	Examples
\	Indicates that the match character is a special character, a literal, or a backreference. (A backreference repeats the previous match.)	相当于转义符 \n matches the newline character,\\ matches \, \( matches (, \) matches )
^	Matches the position at the start of the string.	^A matches A if A is the first character in the string. 匹配输入字符串的开始位置，在方括号表达式中使用，此时它表示不接受该字符集合。
$	Matches the position at the end of the string.	$B matches B if B is the last character in the string. 匹配输入字符串的结尾位置。
*	Matches the preceding character zero or more times.	ba*rk matches brk, bark, baark, and so on.匹配前面的字符0次，1次，多次
+	Matches the preceding character one or more times.	ba+rk matches bark, baark, and so on, but not brk. 匹配前面的字符1次，多次
?	Matches the preceding character zero or one time.	ba?rk matches brk and bark only. 匹配前面的字符0次，1次
{n}	Matches a character exactly n times, where n is an integer.	hob{2}it matches hobbit.(加上自己总共两次) 一个精确地出现次数范围，m=<出现次数<=n，'{m}'表示出现m次，'{m,}'表示至少出现m次。
{n,m}	Matches a character at least n times and at most m times, where n and m are both integers.	hob{2,3}it matches hobbit and hobbbit only.
.	Matches any single character except null.	hob.it matches hobait, hobbit, and so on.(匹配任何单字符)
(pattern)	A subexpression that matches the specified pattern. You use subexpressions to build up complex regular expressions. You can access the individual matches, known as captures, from this type of subexpression.	anatom(y|ies) matches anatomy and anatomies.
x|y	Matches x or y, where x and y are one or more characters.	war|peace matches war or peace.(两者择一)
[abc]	Matches any of the enclosed characters.	[ab]bc matches abc and bbc.(匹配方括号内的字符)
[a-z]	Matches any character in the specified range.	[a-c]bc matches abc, bbc, and cbc.(匹配范围内的字符)
[: :]	Specifies a character class and matches any character in that class.	[:alphanum:] matches alphanumeric characters 0-9, A-Z, and a-z. [:alpha:] matches alphabetic characters A-Z and a-z. [:blank:] matches space or tab. [:digit:] matches digits 0-9.[:graph:] matches non-blank characters.[:lower:] matches lowercase alphabetic characters a-z.[:print:] is similar to [:graph:] except [:print:] includes the space character.[:punct:] matches punctuation characters .,"', and so on.[:space:] matches all whitespace characters.[:upper:] matches all uppercase alphabetic characters A-Z.[:xdigit:] matches characters permissible in a hexadecimal number 0-9, A-F, and a-f.
[..]	Matches one collation element, like a multicharacter element.	No example.
[==]	Specifies equivalence classes.	No example.
\n	This is a backreference to an earlier capture, where n is a positive integer.	(.)\1 matches two consecutive identical characters. The (.) captures any single character except null, and the \1 repeats the capture, matching the same character again, therefore matching two consecutive identical characters.

参考网址:http://zhouwf0726.itpub.net/post/9689/189020

racle的正则表达式(regular expression)简单介绍

目前，正则表达式已经在很多软件中得到广泛的应用，包括*nix（Linux, Unix等），HP等操作系统，PHP，C#，Java等开发环境。

Oracle 10g正则表达式提高了SQL灵活性。有效的解决了数据有效性， 重复词的辨认, 无关的空白检测，或者分解多个正则组成
的字符串等问题。

Oracle 10g支持正则表达式的四个新函数分别是：REGEXP_LIKE、REGEXP_INSTR、REGEXP_SUBSTR、和REGEXP_REPLACE。
它们使用POSIX 正则表达式代替了老的百分号（%）和通配符（_）字符。

特殊字符：
'^' 匹配输入字符串的开始位置，在方括号表达式中使用，此时它表示不接受该字符集合。
'$' 匹配输入字符串的结尾位置。如果设置了 RegExp 对象的 Multiline 属性，则 $ 也匹配 'n' 或 'r'。
'.' 匹配除换行符 n之外的任何单字符。
'?' 匹配前面的子表达式零次或一次。
'*' 匹配前面的子表达式零次或多次。
'+' 匹配前面的子表达式一次或多次。
'( )' 标记一个子表达式的开始和结束位置。
'[]' 标记一个中括号表达式。
'{m,n}' 一个精确地出现次数范围，m=<出现次数<=n，'{m}'表示出现m次，'{m,}'表示至少出现m次。
'|' 指明两项之间的一个选择。例子'^([a-z]+|[0-9]+)$'表示所有小写字母或数字组合成的字符串。
num 匹配 num，其中 num 是一个正整数。对所获取的匹配的引用。
正则表达式的一个很有用的特点是可以保存子表达式以后使用， 被称为Backreferencing. 允许复杂的替换能力
如调整一个模式到新的位置或者指示被代替的字符或者单词的位置. 被匹配的子表达式存储在临时缓冲区中， 
缓冲区从左到右编号, 通过数字符号访问。 下面的例子列出了把名字 aa bb cc 变成
cc, bb, aa.
Select REGEXP_REPLACE('aa bb cc','(.*) (.*) (.*)', '3, 2, 1') FROM dual；
REGEXP_REPLACE('ELLENHILDISMIT
cc, bb, aa
'' 转义符。

字符簇： 
[[:alpha:]] 任何字母。
[[:digit:]] 任何数字。
[[:alnum:]] 任何字母和数字。
[[:space:]] 任何白字符。
[[:upper:]] 任何大写字母。
[[:lower:]] 任何小写字母。
[[:punct:]] 任何标点符号。
[[:xdigit:]] 任何16进制的数字，相当于[0-9a-fA-F]。

各种操作符的运算优先级
转义符
(), (?:), (?=), [] 圆括号和方括号
*, +, ?, {n}, {n,}, {n,m} 限定符
^, $, anymetacharacter 位置和顺序
| “或”操作

正则表达式方法:

The regular expression functions available in Oracle Database 10g.

REGEXP_LIKE(x, pattern [, match_option])

Returns true when the source x matches the regular expression pattern.

You can change the default matching using match_option, which may be set to:

'c', which specifies case sensitive matching (default).默认大小写敏感

'i', which specifies case insensitive matching.大小写不敏感

'n', which allows you to use the match-any-character operator.

'm', which treats x as multiple line.

REGEXP_INSTR(x, pattern [, start [, occurrence [, return_option [, match_option]]]])

Searches for pattern in x and returns the position at which pattern occurs.

You can supply an optional:

start position to begin the search.--开始位置

occurrence that indicates which occurrence of pattern_exp should be returned.--那个位置出现的值应该被返回

return_option that indicates what integer to return. 0 specifies the integer to return is the position of the first character in x; non-zero specifies the integer to return is the position of the character in x after the occurrence.--0表示出现第一个字符的位置。1表示匹配表达式出现后的位置

match_option to change the default matching.--类似与REGEXP_LIKE的表

REGEXP_REPLACE(x, pattern [, replace_string [, start [, occurrence [, match_option]]]])

Searches x for pattern and replaces it with replace_string.

The other options have the same meaning as those shown earlier.

REGEXP_SUBSTR(x, pattern [, start [, occurrence [, match_option]]])

Returns a substring of x that matches pattern, which begins at the position specified by start.

The other options have the same meaning as those shown earlier.

REGEXP_INSTR的使用:

REGEXP_INSTR extends the regular INSTR string function by allowing searches of regular expressions.

The simplest form of this function is:

REGEXP_INSTR(source_string, pattern_to_find)

This part works like the INSTR function.

The general format for the REGEXP_INSTR function with all the options is:

1、source_string is the string in which you wish to search for the pattern.

2、pattern_to_find is the pattern that you wish to search for in a string.

3、position indicates where to start searching in source_string.

4、occurrence indicates which occurrence of the pattern_to_find (in the source_string) you wish to search for.

5、For example, which occurrence of "si" do you want to extract from the source string "Mississippi".

6、return_option can be 0 or 1.

7、If return_option is 0, Oracle returns the first character of the occurrence (this is the default);

8、if return_option is 1, Oracle returns the position of the character following the occurrence.

9、match_parameter allows you to further customize your search.

10、"i" in match_parameter can be used for caseinsensitive matching

11、"c" in match_parameter can be used for casesensitive matching

12、"n" in match_parameter allows the period to match the new line character

13、"m" in match_parameter allows for more than one line in source_string

SELECT REGEXP_INSTR('Mississippi', 'si', 1,2,0,'i') FROM dual;

结果:7

i表示大小写敏感。

SELECT REGEXP_INSTR('Mississippi', 'si', 1,2,1,'i') FROM dual;

结果:9

1表示返回找到的字符串的下个字符开始位置。

SELECT REGEXP_INSTR('abcedfghijklumnoprstuvwxyzabcedhijklumnoprstuvwxyz',
'l[[:alpha:]]{4}') AS RESULT
FROM DUAL;

结果:12

表示查询从1开始的后面任意有四个字符的位置

REGEXP_LIKE的使用:

REGEXP_LIKE(x, pattern [, match_option]) searchs x for the regular expression pattern.

You can provide an optional match_option string to indicate the default matching.

'c', which specifies case sensitive matching (default).大小写敏感

'i', which specifies case insensitive matching.大小写不敏感

'n', which allows you to use the match-any-character operator.

'm', which treats x as multiple line.

WITH DATAS AS
2   (SELECT 'Hello' AS D
FROM DUAL
UNION ALL
SELECT 'hello' FROM DUAL)
SELECT * FROM DATAS WHERE REGEXP_LIKE(DATAS.D, '^h', 'i')

结果:

WITH DATAS AS
(SELECT 'a' AS D
FROM DUAL
4 　　 UNION ALL
SELECT 'b' FROM DUAL)
SELECT * FROM DATAS WHERE REGEXP_LIKE(DATAS.D, '[ab]', 'i')

结果:
a
b