建表

create table commdity(

cid int PRIMARY KEY,

cname VARCHAR(20),

cprice DOUBLE);

create table myuser(

uid INT PRIMARY key,

uname varchar(20),

uaddress varchar(20));

create table list(

uid int,

cid int,

amount int,

CONSTRAINT fk_list_myuser FOREIGN key(uid) REFERENCES myuser(uid),

CONSTRAINT fk_list_commdity FOREIGN key(cid) REFERENCES commdity(cid)

);

insert into myuser values(10,'zhang','大连'),(20,'wang','沈阳');

insert into commdity values(11,'计算机',1000.5),(12,'硬盘',100),(13,'显卡',600);

insert into list values(10,11,50),(20,12,5),(20,13,1);

insert into list values(30,11,40);

select commdity.cname,list.amount,myuser.uname

from myuser,list,commdity

where list.uid=myuser.uid

and list.cid=commdity.cid

and myuser.uname='zhang';