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  • 多表查询

    1.分类表
    create table category(
    cid varchar(32) primary key,
    cname varchar(100)
    ); 

    2.商品表
    create table product(
    pid varchar(32) primary key,
    pname varchar(40),
    price double,
    category_id varchar(32)
    );

    4.
    insert into category(cid,cname) values('c001','家电');
    insert into category(cid,cname) values('c002','服饰');
    insert into category(cid,cname) values('c003','化妆品');

     

    5.

    insert into product(pid,pname,price,category_id) values('p001','联想','5000','c001');

    insert into product(pid,pname,price,category_id) values('p002','海尔','5000','c001');
    insert into product(pid,pname,price,category_id) values('p003','雷神','5000','c001');

    insert into product(pid,pname,price,category_id) values('p004','JACK JONES','800','c002');
    insert into product(pid,pname,price,category_id) values('p005','真维斯','200','c002');
    insert into product(pid,pname,price,category_id) values('p006','花花公子','440','c002');
    insert into product(pid,pname,price,category_id) values('p007','劲霸','2000','c002');

    insert into product(pid,pname,price,category_id) values('p008','香奈儿','800','c003');
    insert into product(pid,pname,price,category_id) values('p009','相宜本草','200','c003');

    6.内连接查询

      显示内连接:select * from catagory (inner) join product on cid=category_id;

      

      隐示内连接:select * from category c ,product p where c.cid=p.category_cid;

      

    7.外连接查询

      左连接:select * from category left outer join product on cid=category_id;

      右连接:select * from category right outer join product on cid=category_id;

      

    8.内连接外连接区别

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  • 原文地址:https://www.cnblogs.com/sacai/p/10604394.html
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