pl/sql存储过程的递归调用,树形数据的展示

--pl/sql的树状结构的存储与展示
drop table article;
create table article(
id number primary key, --id
cont varchar2(4000),
pid number,           --父id
isleaf number(1),     --0代表非叶子节点,1代表叶子节点
alevle number(2)      --深度,层级
);

insert into article values(1,'蚂蚁大战大象',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,'怎么可能',1,0,1);
insert into article values(7,'怎么没有可能',6,1,2);
insert into article values(8,'可能性很大的',6,1,2);
insert into article values(9,'大象进医院了',2,0,2);
insert into article values(10,'护士是蚂蚁',9,1,3);
commit;

--pl/sql存储过程的递归调用,树形数据的展示
--sp_tree_recur(v_pid,v_level);--树的root_id;
create or replace procedure sp_tree_recur(v_pid article.pid%type,v_level binary_integer) is
cursor c is select * from article where pid=v_pid;
v_format_string  varchar2(10000):='';
begin
for c_article in c loop
begin
for i in 1..v_level loop--深度,层级
v_format_string:=v_format_string||'****';
end loop;
dbms_output.put_line(v_format_string||c_article.cont);
if(c_article.isleaf = 0) then --非叶子节点,继续递归
sp_tree_recur(c_article.id,c_article.ALEVLE+1);
end if;
end;
end loop;
end;