Oracle的REGEXP_SUBSTR函數簡單使用方法

REGEXP_SUBSTR延伸SUBSTR函數的功能。讓你搜索一個正則表達式模式字符串。sql

這也類似於REGEXP_INSTR。而是返回子字符串的位置,它返回的子字符串自己。數據庫

語法

Oracle數據庫中的REGEXP_SUBSTR函數的語法是:express

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

參數

source_char

搜索字符串。可以是隨意的數據類型char。VARCHAR2。nchar,CLOB,NCLOB類型markdown

pattern

正則表達式less

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.
* 匹配零個或多個.
+ 匹配一個或多個出現.
? 匹配零次或一次出現.
. 匹配不論什麼字符,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 匹配一個數字字符.
\D 匹配一個非數字字符.
\w 匹配包含下劃線的不論什麼單詞字符.
\W 匹配不論什麼非單詞字符.
\s 匹配不論什麼空白字符。包含空格、製表符、換頁符等等.
\S 匹配不論什麼非空白字符.
\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

可選。搜索在字符串中的開始位置。假設省略,默以爲1。這是第一個位置的字符串。函數

occurrence

可選。它是模式字符串中的第n個匹配位置。假設省略。默以爲1。post

match_parameter

可選。它贊成你改動regexp_substr功能匹配的行爲。它可以是如下的組合:ui

Value Description
‘c’ 區分大寫和小寫的匹配.
‘i’ 不區分大寫和小寫的匹配.
‘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

找出匹配的數字spa

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

如下這個樣例返回指定第三次出現的字符.net

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


做者:itmyhome

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