Mysql中的递归层次查询（父子查询）

-- ---------------------------- 
-- Table structure for `treenodes` 
-- ---------------------------- 
DROP TABLE IF EXISTS `treenodes`; 
CREATE TABLE `treenodes` ( 
  `id` int(11) NOT NULL, 
  `nodename` varchar(20) DEFAULT NULL, 
  `pid` int(11) DEFAULT NULL, 
  PRIMARY KEY (`id`) 
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

-- ---------------------------- 
-- Records of treenodes 
-- ---------------------------- 
INSERT INTO `treenodes` VALUES ('1', 'A', '0'); 
INSERT INTO `treenodes` VALUES ('2', 'B', '1'); 
INSERT INTO `treenodes` VALUES ('3', 'C', '1'); 
INSERT INTO `treenodes` VALUES ('4', 'D', '2'); 
INSERT INTO `treenodes` VALUES ('5', 'E', '2'); 
INSERT INTO `treenodes` VALUES ('6', 'F', '3'); 
INSERT INTO `treenodes` VALUES ('7', 'G', '6'); 
INSERT INTO `treenodes` VALUES ('8', 'H', '0'); 
INSERT INTO `treenodes` VALUES ('9', 'I', '8'); 
INSERT INTO `treenodes` VALUES ('10', 'J', '8'); 
INSERT INTO `treenodes` VALUES ('11', 'K', '8'); 
INSERT INTO `treenodes` VALUES ('12', 'L', '9'); 
INSERT INTO `treenodes` VALUES ('13', 'M', '9'); 
INSERT INTO `treenodes` VALUES ('14', 'N', '12'); 
INSERT INTO `treenodes` VALUES ('15', 'O', '12'); 
INSERT INTO `treenodes` VALUES ('16', 'P', '15'); 
INSERT INTO `treenodes` VALUES ('17', 'Q', '15');

delimiter // 
CREATE FUNCTION `getParLst`(rootId INT)
RETURNS varchar(1000) 

BEGIN
	DECLARE sTemp VARCHAR(1000);
	DECLARE sTempPar VARCHAR(1000); 
	SET sTemp = ''; 
	SET sTempPar =rootId; 
	
	#循环递归
	WHILE sTempPar is not null DO 
		#判断是否是第一个，不加的话第一个会为空
		IF sTemp != '' THEN
			SET sTemp = concat(sTemp,',',sTempPar);
		ELSE
			SET sTemp = sTempPar;
		END IF;

		SET sTemp = concat(sTemp,',',sTempPar); 
		SELECT group_concat(pid) INTO sTempPar FROM treenodes where pid<>id and FIND_IN_SET(id,sTempPar)>0; 
	END WHILE; 
	
RETURN sTemp; 
END
//

delimiter // 
CREATE FUNCTION `getParLst`(rootId INT)
RETURNS varchar(1000) 

BEGIN
	DECLARE sTemp VARCHAR(1000);
    DECLARE sTempChd VARCHAR(1000);

    SET sTemp = '$';
    SET sTempChd =cast(rootId as CHAR);

    WHILE sTempChd is not null DO
    	SET sTemp = concat(sTemp,',',sTempChd);
        SELECT group_concat(id) INTO sTempChd FROM  treeNodes where FIND_IN_SET(pid,sTempChd)>0;
   	END WHILE;
    RETURN sTemp; 
END
//