mysql internal join of all sons of a parent - mysql

Question

I have a table structured as
Id int(10)
Parent int(10) --reference I'd
Name
This table contain organization structure. Example data
Id | parent | name
1 Null organization A
2 1 Office A
3 1 Office B
4 3 Room 1
5 3 Room 2
`
This example simple map that org. A have 2 offices,
Office B have 2 rooms .
Parent field hold either null (if no parent -end node-) or an Id of parent.
I want to fetch all rows of a parent row
I want my query to return all child's and children of children.
Can I do this with one query ?

Answer 1

Unless you have a fixed hierarchy depth, I can't think of how you could do it with one query in MySQL (could always be mistaken). If you have hierarchy depth of less than 255 you can do it with a single call to previously created recursive procedures like below.
Inner Procedure Inner
CREATE PROCEDURE `parent_child`(in `I_Parent` int)
BEGIN
DECLARE `V_done` INT;
DECLARE `V_Id` INT;
DECLARE `V_Parent` INT;
DECLARE `V_Name` VARCHAR(45);
DECLARE `cur1` CURSOR FOR SELECT * FROM `stackoverflow`.`parent_child` WHERE `Parent` = `I_Parent`;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET `V_done` = TRUE;
INSERT INTO `stackoverflow`.`parent_child_temp` SELECT `Id`, `Parent`, `Name` FROM `stackoverflow`.`parent_child` WHERE `Parent` IS NULL AND `Id` = `I_Parent`;
OPEN `cur1`;
read_loop: LOOP
FETCH `cur1` INTO `V_Id`, `V_Parent`, `V_Name` ;
IF `V_done` THEN
LEAVE read_loop;
END IF;
INSERT INTO `stackoverflow`.`parent_child_temp` SELECT `V_Id`, `V_Parent`, `V_Name`;
CALL `stackoverflow`.`parent_child`(V_Id);
END LOOP;
CLOSE `cur1`;
END
Wrapper Procedure Inner
CREATE PROCEDURE `parent_child_wrapper`(in `I_WrapperParent` int)
BEGIN
SET ##SESSION.max_sp_recursion_depth = 255;
DROP TABLE IF EXISTS `stackoverflow`.`parent_child_temp`;
CREATE TEMPORARY TABLE `stackoverflow`.`parent_child_temp` (id int, parent int, name varchar(45));
CALL `stackoverflow`.`parent_child`(`I_WrapperParent`);
SELECT * FROM `stackoverflow`.`parent_child_temp`;
END
Call SQL
CALL stackoverflow.parent_child_wrapper(1);
References
*http://dev.mysql.com/doc/refman/5.0/en/cursors.html
*How I query (with mysql) column names that "unfortunately" have round brackets?
*http://www.sitepoint.com/cursors-mysql-stored-procedures/
*How to echo print statements while executing a sql script
*http://dev.mysql.com/doc/refman/5.6/en/server-system-variables.html#sysvar_max_sp_recursion_depth
*MySql :: stored procedure recursive
*http://www.tutorialspoint.com/mysql/mysql-temporary-tables.htm
*How to get depth in mysql store procedure recursion?