This REGEXP_COUNT() MySQL implementation returns the number of times pattern is matched in expression

REGEXP_COUNT.sql

-- Returns the number of times pattern is matched in expression
-- Author : sfaut <https://github.com/sfaut>
-- Publication date : 2023-04-02
-- Tested with MySQL 8.0.32 (@@sql_mode='ANSI,TRADITIONAL')

DELIMITER ;;

CREATE FUNCTION "REGEXP_COUNT"(expression TEXT, pattern TEXT)
RETURNS INT UNSIGNED
DETERMINISTIC
COMMENT 'Returns the number of times pattern is matched in expression'
BEGIN
	DECLARE result INTEGER UNSIGNED DEFAULT 0;
	DECLARE last_position INTEGER UNSIGNED DEFAULT 1;
	DECLARE expression_length INTEGER UNSIGNED DEFAULT CHAR_LENGTH(expression);

	REPEAT
		SET last_position = REGEXP_INSTR(expression, pattern, last_position, 1, 1);
		IF last_position > 0 THEN
			SET result = result + 1;
		END IF;
	UNTIL last_position = 0 OR last_position > expression_length END REPEAT;

	RETURN result;
END;;