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Oracle® Database SQL Language Reference
11g Release 2 (11.2)

Part Number E17118-03
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REGEXP_INSTR

Syntax

Description of regexp_instr.gif follows
Description of the illustration regexp_instr.gif

Purpose

REGEXP_INSTR extends the functionality of the INSTR function by letting you search a string for a regular expression pattern. The function evaluates strings using characters as defined by the input character set. It returns an integer indicating the beginning or ending position of the matched substring, depending on the value of the return_option argument. If no match is found, then the function returns 0.

This function complies with the POSIX regular expression standard and the Unicode Regular Expression Guidelines. For more information, refer to Appendix D, "Oracle Regular Expression Support".

Examples

The following example examines the string, looking for occurrences of one or more non-blank characters. Oracle begins searching at the first character in the string and returns the starting position (default) of the sixth occurrence of one or more non-blank characters.

SELECT
  REGEXP_INSTR('500 Oracle Parkway, Redwood Shores, CA',
               '[^ ]+', 1, 6) "REGEXP_INSTR"
  FROM DUAL;

REGEXP_INSTR
------------
          37

The following example examines the string, looking for occurrences of words beginning with s, r, or p, regardless of case, followed by any six alphabetic characters. Oracle begins searching at the third character in the string and returns the position in the string of the character following the second occurrence of a seven-letter word beginning with s, r, or p, regardless of case.

SELECT
  REGEXP_INSTR('500 Oracle Parkway, Redwood Shores, CA',
               '[s|r|p][[:alpha:]]{6}', 3, 2, 1, 'i') "REGEXP_INSTR"
  FROM DUAL;

REGEXP_INSTR
------------
          28

The following examples use the subexpr argument to search for a particular subexpression in pattern. The first statement returns the position in the source string of the first character in the first subexpression, which is '123':

SELECT REGEXP_INSTR('1234567890', '(123)(4(56)(78))', 1, 1, 0, 'i', 1) 
"REGEXP_INSTR" FROM DUAL;

REGEXP_INSTR
-------------------
1

The next statement returns the position in the source string of the first character in the second subexpression, which is '45678':

SELECT REGEXP_INSTR('1234567890', '(123)(4(56)(78))', 1, 1, 0, 'i', 2) 
"REGEXP_INSTR" FROM DUAL;

REGEXP_INSTR
-------------------
4

The next statement returns the position in the source string of the first character in the fourth subexpression, which is '78':

SELECT REGEXP_INSTR('1234567890', '(123)(4(56)(78))', 1, 1, 0, 'i', 4) 
"REGEXP_INSTR" FROM DUAL;

REGEXP_INSTR
-------------------
7