Need help for a SQL query - mysql

Question

This is my table structure:
id id_parent id_origin level name
1 0 1 1 PHP
2 0 2 1 Javascript
3 0 3 1 SMARTY
4 0 4 1 HTML
5 1 1 2 Basic
6 1 1 2 Date & Math Function
8 2 2 2 DOM
9 5 1 3 Introduction
10 5 1 3 Session & Cookies
12 2 2 2 Introduction
13 4 4 2 Basic Structure
14 6 1 3 PHP Date Function
16 3 3 2 Basic Syntax
26 4 4 2 Table
I want result like below format
Myfinalstr
-----------
PHP
PHP->Basic
PHP->Basic->Introduction
PHP->Basic->Session & Cookies
PHP->Date & Match Function
PHP->Date & Match Function->PHP Date Function
Javascript
Javascript->DOM
Javascript->Introduction
SMARTY
SMARTY->Basic Syntax
HTML
HTML->Basic Structure
HTML->Table

Answer 1

The following isnt a complete solution but it will get you started:
Example stored procedure call
mysql> call chapter_hier(1);
+----+----------------------+-----------+----------------------+-------+
| id | category_name | id_parent | parent_category_name | depth |
+----+----------------------+-----------+----------------------+-------+
| 1 | PHP | NULL | NULL | 0 |
| 5 | Basic | 1 | PHP | 1 |
| 6 | Date & Math Function | 1 | PHP | 1 |
| 9 | Introduction | 5 | Basic | 2 |
| 10 | Session & Cookies | 5 | Basic | 2 |
| 14 | PHP Date Function | 6 | Date & Math Function | 2 |
+----+----------------------+-----------+----------------------+-------+
6 rows in set (0.00 sec)
$result = $conn->query(sprintf("call chapter_hier(%d)", 1));
Full script and test data
drop table if exists chapters;
create table chapters
(
id smallint unsigned not null primary key,
name varchar(255) not null,
id_parent smallint unsigned null,
key (id_parent)
)
engine = innodb;
insert into chapters (id, name, id_parent) values
(1,'PHP',null),
(2,'Javascript',null),
(3,'SMARTY',null),
(4,'HTML',null),
(5,'Basic',1),
(6,'Date & Math Function',1),
(8,'DOM',2),
(9,'Introduction',5),
(10,'Session & Cookies',5),
(12,'Introduction',2),
(13,'Basic Structure',4),
(14,'PHP Date Function',6),
(16,'Basic Syntax',3),
(26,'Table',4);
drop procedure if exists chapter_hier;
delimiter #
create procedure chapter_hier
(
in p_id smallint unsigned
)
begin
declare v_done tinyint unsigned default 0;
declare v_depth smallint unsigned default 0;
create temporary table hier(
id_parent smallint unsigned,
id smallint unsigned,
depth smallint unsigned default 0
)engine = memory;
insert into hier select id_parent, id, v_depth from chapters where id = p_id;
create temporary table tmp engine=memory select * from hier;
/* http://dev.mysql.com/doc/refman/5.0/en/temporary-table-problems.html */
while not v_done do
if exists( select 1 from chapters c
inner join tmp on c.id_parent = tmp.id and tmp.depth = v_depth) then
insert into hier select c.id_parent, c.id, v_depth + 1 from chapters c
inner join tmp on c.id_parent = tmp.id and tmp.depth = v_depth;
set v_depth = v_depth + 1;
truncate table tmp;
insert into tmp select * from hier where depth = v_depth;
else
set v_done = 1;
end if;
end while;
select
c.id,
c.name as category_name,
p.id as id_parent,
p.name as parent_category_name,
hier.depth
from
hier
inner join chapters c on hier.id = c.id
left outer join chapters p on hier.id_parent = p.id
order by
hier.depth;
drop temporary table if exists hier;
drop temporary table if exists tmp;
end #
delimiter ;
Hope it helps :)