Name
regexp_instr — Returns the first position of the occurrence of a regular-expression pattern in a given string.
Synopsis
integer regexp_instr ( |
in source_string varchar , |
| in pattern varchar , | |
| in start_position integer , | |
| in occurrence integer , | |
| in return_option integer , | |
in match_parameter integer
); |
Description
This function looks for a pattern and returns the first position
of the pattern. Optionally, you can indicate the start_position you want to begin the
search. The occurrence
parameter defaults to 1 unless you indicate that you are looking
for a subsequent occurrence. The default value of the return_option is 0, which returns the
starting position of the pattern; a value of 1 returns the starting
position of the next character following the match.
This function returns the starting position of a pattern, so it works much like the familiar INSTR function. The main difference between the two functions is that REGEXP_INSTR lets you specify a pattern instead of a specific search string; thus providing greater versatility.
Parameters
source_string
The string to search.
pattern
The regular expression to match.
start_position
The position to begin the search from.
occurrence
Defaulting to 1, this parameter describes how many occurrences to look for.
return_option
Default is 0, which returns the starting position of the pattern; a value of 1 returns the starting position of the next character following the match.
match_parameter
Match parameter value.
Returns
This function returns the a substring matching the regular expression.
Examples
Example24.311.Examples
This example uses REGEXP_INSTR()
to return the starting position of the five-digit zip-code pattern
within the string Joe Smith, 10045 Berry Lane, San Joseph, CA
91234. If the regular expression is written as :digit:?{5}, you
will get the house number's starting position instead of the zip
code's, because 10045 is the first occurrence of five consecutive
digits. Therefore, you must anchor the expression to the end of the
line, as indicated with the $ metacharacter, and the function will
display the starting position of the zip code regardless of the
number of digits for the house number.
SELECT REGEXP_INSTR('Joe Smith, 10045 Berry Lane, San Joseph, CA 91234',
'[[:digit:]]{5}\$')
AS rx_instr;
RX_INSTR
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45
![[Note]](images/note.png)