1、建立測試表；

create table company(companyId number, companyName varchar2(20), contacts varchar2(20));

create table users(userId number, companyId number, userName varchar2(20), userAge number, address varchar2(20));

2、插入測試資料；

insert into company values (1,"騰訊科技","馬化騰");

insert into company values (2,"微軟公司","鮑威爾");

insert into company values (3,"新浪科技","小明" );

insert into users values (1,1,"jack",23 , "上海");

insert into users values (2,1,"jack2", 23, "上海");

insert into users values (3,2,"jack3", 23, "上海");

insert into users values (4,2,"jack4", 23, "上海");

insert into users values (5,3,"jack5", 23, "上海");

insert into users values (6,3,"jack6", 23, "上海");

3、查詢表中資料；

select * from users;

4、編寫sql，關聯兩張表；select * from users t , company b where t.companyid = b.companyid and t.companyid = 1;