make a new column in sql by appending values in existing column code example

Example 1: append column sql

ALTER TABLE table_name
ADD column_name datatype;

--example
ALTER TABLE Customers
ADD Email varchar(255);

Example 2: add new column after in sql

ALTER TABLE `fb_banners`
ADD `city_id` BIGINT(20) UNSIGNED NULL DEFAULT NULL AFTER `BannerID`,
ADD INDEX `Foreign_city_id_banners` (`city_id`) USING BTREE,
ADD CONSTRAINT `Foreign_city_id_banners` FOREIGN KEY (`city_id`) REFERENCES `foodsafari`.`fb_cities` (`id`) ON UPDATE CASCADE ON DELETE CASCADE;