MySQL recursive tree search

Question

I have a database with a tree of names that can go down a total of 9 levels deep and I need to be able to search down a signal branch of the tree from any point on the branc

Answer 1

You can do this with a stored procedure as follows:

Example calls

mysql> call names_hier(1, 'a');
+----+----------+--------+-------------+-------+
| id | emp_name | parent | parent_name | depth |
+----+----------+--------+-------------+-------+
|  2 | ali      |      1 | f00         |     1 |
|  8 | anna     |      6 | keira       |     4 |
+----+----------+--------+-------------+-------+
2 rows in set (0.00 sec)

mysql> call names_hier(3, 'k');
+----+----------+--------+-------------+-------+
| id | emp_name | parent | parent_name | depth |
+----+----------+--------+-------------+-------+
|  6 | keira    |      5 | eva         |     2 |
+----+----------+--------+-------------+-------+
1 row in set (0.00 sec)

$sqlCmd = sprintf("call names_hier(%d,'%s')", $id, $name);  // dont forget to escape $name
$result = $db->query($sqlCmd);

Full script

drop table if exists names;
create table names
(
id smallint unsigned not null auto_increment primary key,
name varchar(255) not null,
parent smallint unsigned null,
key (parent)
)
engine = innodb;

insert into names (name, parent) values
('f00',null), 
  ('ali',1), 
  ('megan',1), 
      ('jessica',3), 
      ('eva',3), 
         ('keira',5), 
            ('mandy',6), 
            ('anna',6);

drop procedure if exists names_hier;

delimiter #

create procedure names_hier
(
in p_id smallint unsigned,
in p_name varchar(255)
)
begin

declare v_done tinyint unsigned default(0);
declare v_dpth smallint unsigned default(0);

set p_name = trim(replace(p_name,'%',''));

create temporary table hier(
 parent smallint unsigned, 
 id smallint unsigned, 
 depth smallint unsigned
)engine = memory;

insert into hier select parent, id, v_dpth from names where id = p_id;

/* http://dev.mysql.com/doc/refman/5.0/en/temporary-table-problems.html */

create temporary table tmp engine=memory select * from hier;

while not v_done do

    if exists( select 1 from names n inner join tmp on n.parent = tmp.id and tmp.depth = v_dpth) then

        insert into hier select n.parent, n.id, v_dpth + 1 
            from names n inner join tmp on n.parent = tmp.id and tmp.depth = v_dpth;

        set v_dpth = v_dpth + 1;            

        truncate table tmp;
        insert into tmp select * from hier where depth = v_dpth;

    else
        set v_done = 1;
    end if;

end while;


select 
 n.id,
 n.name as emp_name,
 p.id as parent,
 p.name as parent_name,
 hier.depth
from 
 hier
inner join names n on hier.id = n.id
left outer join names p on hier.parent = p.id
where
 n.name like concat(p_name, '%');

drop temporary table if exists hier;
drop temporary table if exists tmp;

end #

delimiter ;

-- call this sproc from your php

call names_hier(1, 'a');
call names_hier(3, 'k');