MySQL对于递归的一个问题

mysql本身不支持递归语法，但可通过自连接变相实现一些简单的递归

--递归小方法：临时表和普通表的不同方法
--这题使用的是2次临时表查询父节点的递归 

drop table if exists test;
create table test(
id varchar(100),
name varchar(20),
parentid varchar(100)
);
insert test select
'13ed38f1-3c24-dd81-492f-673686dff0f3', '大学教师', '37e2ea0a-1c31-3412-455a-5e60b8395f7d' union all select 
'1ce203ac-ee34-b902-6c10-c806f0f52876','小学教师', '37e2ea0a-1c31-3412-455a-5e60b8395f7d' union all select 
'37e2ea0a-1c31-3412-455a-5e60b8395f7d', '教师' ,      null                union all select 
'c877b7ea-4ed3-f472-9527-53e1618cb1dc', '高数老师', '13ed38f1-3c24-dd81-492f-673686dff0f3' union all select 
'ce50a471-2955-00fa-2fb7-198f6b45b1bd', '中学教师', '37e2ea0a-1c31-3412-455a-5e60b8395f7d';
 
delimiter $$
 
create procedure usp_ser(in idd varchar(100))
begin
declare lev int;
set lev=1;
drop table if exists tmp1;
drop table if exists tmp2;
CREATE TEMPORARY TABLE tmp1(id varchar(100),name varchar(20),parentid varchar(100),levv int);
CREATE TEMPORARY TABLE tmp2(pid varchar(100));
insert tmp2 select parentid from test where id=idd;
insert tmp1 select t.* , lev from test t join tmp2 a on t.id=a.pid;
    while exists(select 1 from tmp2 )
do
truncate tmp2;
set lev=lev+1;
insert tmp2 select t.id from test t join tmp1 a on t.id=a.parentid and a.levv=lev-1;
insert tmp1 select t.*,lev from test t join tmp2 a on t.id=a.pid;
end while ;
select id,name,parentid from tmp1;
end;
$$
 
delimiter ;
 
 call usp_ser('c877b7ea-4ed3-f472-9527-53e1618cb1dc');
+--------------------------------------+----------+--------------------------------------+

关键词：MySQL对于递归的一个问题