ESQL: check if string contains only one unique character

isMadeOfOneChar.esql

	CREATE FUNCTION isMadeOfOneChar(IN text CHAR, IN dividerChar CHAR) RETURNS BOOLEAN
	BEGIN
		DECLARE index INT 1;
		DECLARE textLength INT LENGTH(text);
		DECLARE currentChar CHAR;
		
		-- If empty string, return false
		IF textLength = 0 THEN 
			RETURN FALSE;
		END IF;
		
		WHILE index <= textLength DO
			SET currentChar = SUBSTRING(text FROM index FOR 1);
			IF currentChar <> dividerChar THEN
				RETURN FALSE;
			END IF;
			SET index = index + 1;
		END WHILE;
		
		RETURN TRUE;
	END;