convert comma separated string into temporary table with individual rows

split_string.sql

DROP procedure IF EXISTS split_string;

DELIMITER $$
CREATE PROCEDURE split_string (list TEXT)
BEGIN
  DECLARE max INT DEFAULT 0;
  DECLARE i INT DEFAULT 1;
  DECLARE elem INT DEFAULT 0;

  SET max = length(list) - length(replace(list, ',', ''));
  WHILE i < max DO
    SET elem = SUBSTRING_INDEX(SUBSTRING_INDEX(list, ',', i), ',', -1);
    INSERT IGNORE INTO table_destination (target_column) VALUES(elem);
    SET i = i + 1;
  END WHILE;
END;$$
DELIMITER ;