MySQL - Generate Random String With Desired Length Function script

fn_generate_random_code.sql

DELIMITER $$
DROP FUNCTION IF EXISTS fn_generate_random_code $$
CREATE FUNCTION fn_generate_random_code (desired_code_len INTEGER) RETURNS VARCHAR(100)
NO SQL
BEGIN
	SET @possible_characters = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ';
	SET @len =  LENGTH(@possible_characters);
    SET @random_code = '';
	append_char_to_random_code: LOOP
		IF LENGTH(@random_code) >= desired_code_len THEN
			LEAVE append_char_to_random_code;
		END IF;
		SET @random_char_pos = FLOOR(RAND()*(@len - 0 + 1) + 0);
		SET @extracted_char = SUBSTRING(@possible_characters, @random_char_pos, 1);
		SET @random_code = CONCAT(@random_code, @extracted_char);
	END LOOP;
	RETURN @random_code;
END $$

Execute by calling the function with expected string len
SELECT fn_generate_random_code(6); , this will produce a 6-length random string with pattern contains characters in the @possible_characters variable, which is 0-9 and A-Z