REGEXP_INSTR searches a string for a regular pattern. It can return an integer indicating either the beginning or the ending position of the matched substring. If no match is found, the function returns 0.
The function evaluates strings using characters as defined by the input character set.
REGEXP_INSTR (source_char, pattern [, position [, occurrence [, return_option [, match_parameter ] ] ] ] )
source_char is the text expression to search.
pattern is the string to search for. A period matches any character. For a list of operators, refer to the Oracle Database SQL Language Reference, Appendix D, Oracle Regular Expression Support.
position is a nonzero integer indicating the character of
source_char where the function begins the search. When
position is negative, then the function counts and searches backward from the end of string. The default value of
position is 1, which means that the function begins searching at the first character of
occurrence is an integer indicating which occurrence of
pattern the function should search for. The value of
occurrence must be positive. The default values of
occurrence is 1, meaning the function searches for the first occurrence of
return_option is either 0 to return the position of the match (default), or 1 to return the position of the character following the match.
match_parameter is a text literal that lets you change the default matching behavior of the function. You can specify one or more of the following values:
c: Case-sensitive matching.
i: Case-insensitive matching.
m: Treat the source string as multiple lines. The function interprets
$ as the start and end, respectively, of any line anywhere in the source string, rather than only at the start or end of the entire source string. By default, the function treats the source string as a single line.
n: New-line character is among the characters matched by a period (the wildcard character). By default, it is not.
x: Ignore whitespace characters.
REGEXP_INSTR('Mississippi', 'i', 1, 3) searches the string
Mississippi for the third instance of the letter
i, beginning the search at the first letter. It returns the value