DELIMITER $$
CREATE DEFINER=`root`@`localhost` PROCEDURE `set_columns`()
BEGIN
    DECLARE i INT DEFAULT 1;
		WHILE i<201 DO
			ALTER TABLE `wafer_production`.`list` ADD `$i` INT;
			SET i=i+1;
		END WHILE;
	END$$
DELIMITER ;

Error Code: 1060. Duplicate column name '$i'