mysql数据库实现类似oracle connect by prior的查询
--注下面的语句用到了表
DROP TABLE IF EXISTS `a_sys_org`;
CREATE TABLE `a_sys_org` (
  `org_id` varchar(32) NOT NULL COMMENT '机构号',
  `org_name` varchar(256) NOT NULL COMMENT '机构名称',
  `parent_org_id` varchar(32) NOT NULL COMMENT '父机构号',
  PRIMARY KEY (`org_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='系统机构表';


-- 方法1，函数实现
-- 注意  SELECT getChildOrg('00010');
-- 最大支持字符串连接102400

DROP FUNCTION IF EXISTS getChildidList;
CREATE FUNCTION getChildidList(rootId VARCHAR(32))
RETURNS text
BEGIN
DECLARE sTemp text;
DECLARE sTempChd text;
SET@@group_concat_max_len = 102400;
SET sTemp = '$';
SET sTempChd = rootId;

WHILE sTempChd IS NOT NULL DO
SET sTemp = concat(sTemp, ',', sTempChd);
SELECT
group_concat(org_id) INTO sTempChd
FROM
a_sys_org
WHERE
FIND_IN_SET(parent_org_id, sTempChd) > 0;
END WHILE;
SET@@group_concat_max_len = 1024;
RETURN SUBSTRING(sTemp,3);
END




-- 方法2，存储过程+中间表
-- 存储过程实现mysql递归查询，类似oracle start with connect by prior
-- 注意  call getChildOrg('00010');
-- 递归有深度限制，最大是255层

DROP PROCEDURE IF EXISTS getChildOrg;
CREATE PROCEDURE getChildOrg (IN rootid VARCHAR(32))
BEGIN
DECLARE _level_var INT;

DROP TABLE IF EXISTS temp_child_list;
CREATE TABLE temp_child_list (
_id VARCHAR(32),
_level INT
);
SET _level_var = 0;
  INSERT INTO temp_child_list (_id, _level) VALUE(rootid,_level_var);
SET _level_var = _level_var + 1;
INSERT INTO temp_child_list (_id, _level)
SELECT
org_id,
_level_var
FROM
a_sys_org
WHERE
parent_org_id = rootid;
WHILE ROW_COUNT() > 0
DO
SET _level_var = _level_var + 1;
INSERT INTO temp_child_list SELECT
a.org_id,
_level_var
FROM
a_sys_org a,
temp_child_list b
WHERE
a.parent_org_id = b._id
AND b._level = _level_var - 1;
END WHILE;
  SELECT _id FROM temp_child_list ORDER BY _level;
  DROP TABLE IF EXISTS temp_child_list;
END;


-- 方法3，存储过程+临时表
-- 存储过程实现mysql递归查询，类似oracle start with connect by prior
-- 注意  call getChildOrg('00010');
-- 递归有深度限制，最大是255层
-- 此存储过程利用了临时表


DROP PROCEDURE IF EXISTS showChildList;
CREATE PROCEDURE showChildList (IN rootId VARCHAR(32))
BEGIN
  SET@@max_sp_recursion_depth=99;
DROP TEMPORARY TABLE IF EXISTS temp_child_list;
CREATE TEMPORARY TABLE temp_child_list ( sno INT PRIMARY KEY auto_increment, _id VARCHAR (32), _depth INT );
-- 插入当前节点
INSERT INTO temp_child_list (_id, _depth) VALUES (rootId ,- 1);
-- 插入子节点
CALL createChildList (rootId, 0);
SELECT o.org_id FROM temp_child_list t, a_sys_org o WHERE t._id = o.org_id ORDER BY t.sno;
END;
DROP PROCEDURE IF EXISTS createChildList;
CREATE PROCEDURE createChildList ( IN rootId VARCHAR (32), IN depth_var INT )
BEGIN
DECLARE done INT DEFAULT 0;
DECLARE b VARCHAR (32);
DECLARE cur1 CURSOR FOR SELECT org_id FROM a_sys_org WHERE parent_org_id = rootId;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
INSERT INTO temp_child_list (_id, _depth) SELECT org_id, depth_var FROM a_sys_org WHERE parent_org_id = rootId;
OPEN cur1;
FETCH cur1 INTO b;
WHILE done = 0 DO CALL createChildList (b, depth_var + 1);
FETCH cur1 INTO b;
END WHILE;
CLOSE cur1;
END;