select 名称,品牌,用户名 from ordered,product,brands,user where ordered.productid=product. productid and ordered.userid=user.userid and product.pp=brands.pp;
ordered(id productid userid) product(id productid pp xh xl) brands(id pp name) user(userid username)用一条SQL语句查出ordered中所有产品的名称,品牌,用户名.(不是编号) select p.xl -- 产品名称? , b.name -- 品牌? , u.username from ordered o join product p on o.productid=p.productid join brands b on p.id=b.id and p.pp=b.pp -- Join On(id, pp)? join user u on o.userid=u.userid
product(id productid pp xh xl)
brands(id pp name)
user(userid username)用一条SQL语句查出ordered中所有产品的名称,品牌,用户名.(不是编号) select p.xl -- 产品名称?
, b.name -- 品牌?
, u.username
from ordered o
join product p on o.productid=p.productid
join brands b on p.id=b.id and p.pp=b.pp -- Join On(id, pp)?
join user u on o.userid=u.userid