ecco una semplice procedura memorizzata non ricorsiva che fa il lavoro:
drop table if exists employees;
create table employees
(
emp_id smallint unsigned not null auto_increment primary key,
name varchar(255) not null,
boss_id smallint unsigned null,
key (boss_id)
)
engine = innodb;
insert into employees (name, boss_id) values
('f00',null),
('ali later',1),
('megan fox',1),
('jessica alba',3),
('eva longoria',3),
('keira knightley',5),
('liv tyler',6),
('sophie marceau',6);
drop procedure if exists employees_hier;
delimiter #
create procedure employees_hier
(
in p_emp_id smallint unsigned
)
begin
declare v_done tinyint unsigned default(0);
declare v_dpth smallint unsigned default(0);
create temporary table hier(
boss_id smallint unsigned,
emp_id smallint unsigned,
depth smallint unsigned
)engine = memory;
insert into hier select boss_id, emp_id, v_dpth from employees where emp_id = p_emp_id;
/* http://dev.mysql.com/doc/refman/5.0/en/temporary-table-problems.html */
create temporary table emps engine=memory select * from hier;
while not v_done do
if exists( select 1 from employees e inner join hier on e.boss_id = hier.emp_id and hier.depth = v_dpth) then
insert into hier select e.boss_id, e.emp_id, v_dpth + 1
from employees e inner join emps on e.boss_id = emps.emp_id and emps.depth = v_dpth;
set v_dpth = v_dpth + 1;
truncate table emps;
insert into emps select * from hier where depth = v_dpth;
else
set v_done = 1;
end if;
end while;
select
e.emp_id,
e.name as emp_name,
p.emp_id as boss_emp_id,
p.name as boss_name,
hier.depth
from
hier
inner join employees e on hier.emp_id = e.emp_id
left outer join employees p on hier.boss_id = p.emp_id;
drop temporary table if exists hier;
drop temporary table if exists emps;
end #
delimiter ;
-- call this sproc from your php
call employees_hier(1);
