Get tree path in MySQL table -

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perhaps easiest approach manage hierarchical data in mysql databases adjacency list model. is, give every node parent:

create table category( category_id int auto_increment primary key, name varchar(20) not null, parent int default null);

it easy parent node, or if there maximum tree depth, can whole tree using this: 

select concat_ws('/', `t3`.`name`, `t2`.`name`, `t1`.`name`) `path` category t1 left join category t2 on t2.parent = t1.category_id left join category t3 on t3.parent = t2.category_id left join category t4 on t4.parent = t3.category_id t1.name = 'xxxxx';

that's enough in many cases, how can generalize solution trees deeper 3 nodes? i.e. may have path "electronics/audio/transmiter/fm/motorola".

is possible 1 query?

here's simple non recursive stored procedure job:

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 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 hier select boss_id, emp_id, v_dpth employees 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 * hier;  while not v_done      if exists( select 1 employees e inner join hier on e.boss_id = hier.emp_id , hier.depth = v_dpth)          insert hier select e.boss_id, e.emp_id, v_dpth + 1              employees e inner join emps on e.boss_id = emps.emp_id , emps.depth = v_dpth;          set v_dpth = v_dpth + 1;                      truncate table emps;         insert emps select * hier depth = v_dpth;      else         set v_done = 1;     end if;  end while;  select   e.emp_id,  e.name emp_name,  p.emp_id boss_emp_id,  p.name boss_name,  hier.depth   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 sproc php  call employees_hier(1);

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