树状结构的存储与展示(利用递归)：
创建论坛表存储文章：
create table article(
id number primary key,
cont varchar2(4000),
pid number, //父节点
isleaf number(1), //0代表非叶子节点，1代表叶子节点
alevel number(2) //所属等级
)
创建存储过程用树状结构存储文章：
create or replace procedure p(v_pid article.pid%type,v_level binary_integer) is
cursor c is select * from article where pid = v_pid;
v_preStr varchar2(1024) := '';
begin
for i in 1..v_level loop
v_preStr := v_preStr || '****';
end loop;
for v_article in c loop
dbms_output.put_line(v_preStr || v_article.cont);
if(v_article.isleaf = 0) then
p(v_article.id,v_level + 1);
end if;
end loop;
end;
输入文章：
insert into article values(1,'瞎说',0,0,0);
insert into article values(2,'大象被打趴下了',1,0,1);
insert into article values(3,'蚂蚁也不好过',2,1,2);
insert into article values(4,'瞎说',2,0,2);
insert into article values(5,'没有瞎说',4,1,3);
insert into article values(6,'大象进医院了',1,0,1);
insert into article values(7,'护士是蚂蚁',6,1,2);
insert into article values(8,'怎么可能',6,1,2);
insert into article values(9,'怎么没有可能',2,0,2);
insert into article values(10'可能性是很大的',9,1,3);
最后得出结果。
_____mosquito.eq
