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
Oracle數據庫中的REGEXP_SUBSTR函數的語法是:express
REGEXP_SUBSTR(source_char, pattern [, position [, occurrence [, match_parameter ]]])
搜索字符串。可以是隨意的數據類型char。VARCHAR2。nchar,CLOB,NCLOB類型markdown
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. |
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
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
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. |
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