Oracle的REGEXP_SUBSTR函数简单用法

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Oracle的REGEXP_SUBSTR函数简单用法

来源: 作者: 时间:2016-01-13 16:39 【

REGEXP_SUBSTR延伸SUBSTR函数的功能,让你搜索一个正则表达式模式字符串。这也类似于REGEXP_INSTR,而是返回子字符串的位置,它返回的子字符串本身。语法Oracle数据库中的REGEXP_SUBSTR函数的语

REGEXP_SUBSTR延伸SUBSTR函数的功能,让你搜索一个正则表达式模式字符串。

这也类似于REGEXP_INSTR,而是返回子字符串的位置,它返回的子字符串本身。

语法

Oracle中的REGEXP_SUBSTR函数的语法是:

REGEXP_SUBSTR(source_char, pattern [, position [, occurrence [, match_parameter ]]])

参数

source_char

搜索字符串。可以是任意的数据类型char,VARCHAR2,nchar,CLOB,NCLOB类型

pattern

正则表达式

Value Description
^ Matches the beginning of a string. If used with a match_parameter of ‘m’, it matches the start of a line anywhere within expression.
$ Matches the end of a string. If used with a match_parameter of ‘m’, it matches the end of a line anywhere within expression.
* 匹配零个或多个.
+ 匹配一个或多个出现.
? 匹配零次或一次出现.
. 匹配任何字符,除了空.
| Used like an "OR" to specify more than one alternative.
[ ] Used to specify a matching list where you are trying to match any one of the characters in the list.
[^ ] Used to specify a nonmatching list where you are trying to match any character except for the ones in the list.
( ) Used to group expressions as a subexpression.
{m} Matches m times.
{m,} Matches at least m times.
{m,n} Matches at least m times, but no more than n times.
\n n is a number between 1 and 9. Matches the nth subexpression found within ( ) before encountering \n.
[..] Matches one collation element that can be more than one character.
[::] Matches character classes.
[==] Matches equivalence classes.
\d 匹配一个数字字符.
\D 匹配一个非数字字符.
\w 匹配包括下划线的任何单词字符.
\W 匹配任何非单词字符.
\s 匹配任何空白字符,包括空格、制表符、换页符等等.
\S 匹配任何非空白字符.
\A Matches the beginning of a string or matches at the end of a string before a newline character.
\Z Matches at the end of a string.
*? Matches the preceding pattern zero or more occurrences.
+? Matches the preceding pattern one or more occurrences.
?? Matches the preceding pattern zero or one occurrence.
{n}? Matches the preceding pattern n times.
{n,}? Matches the preceding pattern at least n times.
{n,m}? Matches the preceding pattern at least n times, but not more than m times.

position

可选。搜索在字符串中的开始位置。如果省略,默认为1,这是第一个位置的字符串。

occurrence

可选。它是模式字符串中的第n个匹配位置。如果省略,默认为1。

match_parameter

可选。它允许你修改regexp_substr功能匹配的行为。它可以是以下的组合:

Value Description
‘c’ 区分大小写的匹配.
‘i’ 不区分大小写的匹配.
‘n’ Allows the period character (.) to match the newline character. By default, the period is a wildcard.
‘m’ expression is assumed to have multiple lines, where ^ is the start of a line and $ is the end of a line, regardless of the position of those characters in expression. By default, expression is assumed to be a single line.
‘x’ Whitespace characters are ignored. By default, whitespace characters are matched like any other character.

Examples

找出匹配的数字

SELECT REGEXP_SUBSTR ('hello my phone is 520 ', '[0-9]+') FROM dual; --520

下面这个例子返回指定第三次出现的字符

SELECT REGEXP_SUBSTR ('i like beijing tiananmen', '(\S*)(\s)', 1, 3)
FROM dual;    --beijing
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