--特点存储好,查询速度慢
create table tree(a int,b int);
insert into tree values (1,null);
insert into tree values (2,1);
insert into tree values (3,1);
insert into tree values (4,2);
--特点存储冗余,查询速度快
create table tree(a varchar2(50));
insert into tree values('01');
insert into tree values('01001');
insert into tree values('01002');
insert into tree values('01001001');
select flag||depname from (select ' ' flag,depid,depname from dali.dep where depid like '%00' union all select ' ',depid,depname from dali.dep where depid not like '%00' union all select ' ',depid,name from dali.emp) order by depid;
insert into dali.dep values(100,'人力资源部');
insert into dali.dep values(101,'人事科');
insert into dali.dep values(102,'档案室');
insert into dali.dep values(200,'软件开发部');
insert into dali.dep values(201,'技术支持班');
insert into dali.dep values(202,'开发组');
insert into dali.emp values(201,'唐五');
insert into dali.emp values(201,'窦六');
insert into dali.emp values(102,'李四');
insert into dali.emp values(202,'黄七');
insert into dali.emp values(101,'王二');
insert into dali.emp values(101,'张三');