sql语句 扩展

1....

insert  .......select......

将查询的结果添加到表中

insert into tdb_goods_cates(cate_name) select goods_cate from tdb_goods group by goods_cate;

2...

多表更新，根据另一张表更新本表

update .... inner join....... on  条件.. set................;

update tdb_goods inner join tdb_goods_cates on goods_cate = cate_name set goods_cate=cate_id;

当字段名相同时，需要在字段前面加  表名.  或将表as 别名   加  别名.

update tdb_goods as g  inner join tdb_goods_brands as b on g.brand_name=b.brand_name set g.brand_name=b.brand_id;

3...

create......select....

1.....的加强，直接创建表

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;