REGEXP_COUNT function - AWS Clean Rooms
SyntaxArgumentsReturn typeExamples

REGEXP_COUNT function

Searches a string for a regular expression pattern and returns an integer that indicates the number of times the pattern occurs in the string. If no match is found, then the function returns 0.

Syntax

REGEXP_COUNT ( source_string, pattern [, position [, parameters ] ] )

Arguments

source_string

A string expression, such as a column name, to be searched.

pattern

A string literal that represents a regular expression pattern.

position

A positive integer that indicates the position within source_string to begin searching. The position is based on the number of characters, not bytes, so that multibyte characters are counted as single characters. The default is 1. If position is less than 1, the search begins at the first character of source_string. If position is greater than the number of characters in source_string, the result is 0.

parameters

One or more string literals that indicate how the function matches the pattern. The possible values are the following:

  • c – Perform case-sensitive matching. The default is to use case-sensitive matching.

  • i – Perform case-insensitive matching.

  • p – Interpret the pattern with Perl Compatible Regular Expression (PCRE) dialect.

Return type

Integer

Example

The following example counts the number of times a three-letter sequence occurs.

SELECT regexp_count('abcdefghijklmnopqrstuvwxyz', '[a-z]{3}');  

 regexp_count
 --------------
            8

The following example counts the number of times the top-level domain name is either org or edu. 

SELECT email, regexp_count(email,'@[^.]*\\.(org|edu)')FROM users
ORDER BY userid LIMIT 4;

                     email                     | regexp_count
-----------------------------------------------+--------------
 Etiam.laoreet.libero@sodalesMaurisblandit.edu |            1
 Suspendisse.tristique@nonnisiAenean.edu       |            1
 amet.faucibus.ut@condimentumegetvolutpat.ca   |            0
 sed@lacusUtnec.ca                             |            0

The following example counts the occurrences of the string FOX, using case-insensitive matching.

SELECT regexp_count('the fox', 'FOX', 1, 'i');

 regexp_count
 --------------
            1

The following example uses a pattern written in the PCRE dialect to locate words containing at least one number and one lowercase letter. It uses the ?= operator, which has a specific look-ahead connotation in PCRE. This example counts the number of occurrences of such words, with case-sensitive matching. 

SELECT regexp_count('passwd7 plain A1234 a1234', '(?=[^ ]*[a-z])(?=[^ ]*[0-9])[^ ]+', 1, 'p');

 regexp_count
 --------------
            2

The following example uses a pattern written in the PCRE dialect to locate words containing at least one number and one lowercase letter. It uses the ?= operator, which has a specific connotation in PCRE. This example counts the number of occurrences of such words, but differs from the previous example in that it uses case-insensitive matching.

SELECT regexp_count('passwd7 plain A1234 a1234', '(?=[^ ]*[a-z])(?=[^ ]*[0-9])[^ ]+', 1, 'ip');

 regexp_count
 --------------
            3