Oracle中国移动经典面试题（附代码跟两种答案）

/*
中国移动sql面试题：

create table test(
   id number(10) primary key,
   type number(10) ,
   t_id number(10),
   value varchar2(6)
);

insert into test values(100,1,1,'张三');
insert into test values(200,2,1,'男');
insert into test values(300,3,1,'50');

insert into test values(101,1,2,'刘二');
insert into test values(201,2,2,'男');
insert into test values(301,3,2,'30');

insert into test values(102,1,3,'刘三');
insert into test values(202,2,3,'女');
insert into test values(302,3,3,'10');

select * from test;
*/

/*
利用一条sql语句将上表的数据显示为如下内容：
姓名     性别     年龄
----------------------
张三     男      50
刘二     男      30
刘三     女      10
*/

--使用分组方式
select max(decode(type, 1, value)) "姓名",
       max(decode(type, 2, value)) "性别",
       max(decode(type, 3, value)) "年龄"
  from test
 group by t_id

--使用表连接方式
select t1.value "姓名",t2.value "性别",t3.value "年龄" from
(select value,t_id from test where type = 1) t1 ,
(select value,t_id from test where type = 2) t2 ,
(select value,t_id from test where type = 3) t3 where t1.t_id = t2.t_id and t1.t_id = t3.t_id