CREATE DEFINER=`root`@`%` PROCEDURE `add_column`(IN tableName VARCHAR(100), IN columnName VARCHAR(100), IN addSql VARCHAR(300))
BEGIN
DECLARE target_database VARCHAR(100);
SELECT DATABASE() INTO target_database;
IF NOT EXISTS (SELECT * FROM information_schema.columns WHERE table_schema = target_database AND table_name = tableName AND column_name = columnName) THEN
set @statement = CONCAT(addSql);
PREPARE STMT FROM @statement;
EXECUTE STMT;
END IF;
END