创建数据表的同时将查询到的数据写入到表中
CREATE TABLE [IF NOT EXISTS] tbl_name
[(create_definition,...)]
select_statement
1、两步实现tdb_goods_brands表的创建和更新
CREATE TABLE tdb_goods_brands(
brand_id SMALLINT UNSIGNED PRIMARY KEY AUTO_INCREMENT,
brand_name VARCHAR(40) NOT NULL
)
SELECT brand_name FROM tdb_goods GROUP BY brand_name;
2、参照tdb_goods_brands表更新tdb_goods表：使用AS起别名，用于区分brand_name
UPDATE tdb_goods AS g INNRE JOIN tdb_goods_brands AS b ON g.brand_name = b.brand_name
SET g.brand_name = b.brand_id;
由于这节中修改了tdb_goods表中brand_name和上节的goods_cate 里面的内容，但是，brand_name和goods_cate的类型依然是VARCHAR,所以还要修改字段的类型：
ALTER TABLE tdb_goods
CHANGE goods_cate cate_id SMALLINT UNSIGNED NOT NULL,
CHANGE brand_name brand_id SMALLINT UNSIGNED NOT NULL;