MySQL-递归查询方法解析

MySQL-递归查询方法解析，兄弟连教育（www.lampbrother.net）帮大家做了个简单的整理：有需要的朋友可以参考下哈。


首先
表结构和数据

CREATE TABLE `class` (  `classid` int(11) NOT NULL AUTO_INCREMENT,  `banji` int(11) DEFAULT NULL COMMENT '0',  `nianji` varchar(255) DEFAULT NULL,  PRIMARY KEY (`classid`)) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8;-- ------------------------------ Records of class-- ----------------------------INSERT INTO `class` VALUES ('1', '0', '1');INSERT INTO `class` VALUES ('2', '1', '2');INSERT INTO `class` VALUES ('3', '1', 'f');INSERT INTO `class` VALUES ('4', '2', 'd');INSERT INTO `class` VALUES ('5', '3', 's');INSERT INTO `class` VALUES ('6', '0', 'a');INSERT INTO `class` VALUES ('7', '6', 'q');INSERT INTO `class` VALUES ('8', '7', 'h');INSERT INTO `class` VALUES ('9', '5', '额');INSERT INTO `class` VALUES ('10', '4', '121');

方法解析1
一级写一个查询结果联合起来

SELECT * from class WHERE classid =1UNIONSELECT * FROM class where banji in(SELECT classid from class  WHERE classid =1 )UNION SELECT * FROM class where banji in (SELECT classid FROM class where banji in(SELECT classid from class  WHERE classid =1))

方法解析2
使用函数方法
创建函数来获取个节点的值

CREATE FUNCTION `selectTree`(`id` int) RETURNS varchar(2000)BEGIN #Routine body goes here... DECLARE st VARCHAR(4000); DECLARE stcc VARCHAR(2000);#给st赋初值不能null，null会没有返回值 set st=''; set stcc=id;#判断stcc的是否为null WHILE stcc is not NULL DO#拼接字符串赋值给st SET st=CONCAT(st,',',stcc); SELECT GROUP_CONCAT(classid) INTO stcc FROM class where FIND_IN_SET(banji,stcc)>0;END WHILE; RETURN st;END;

调用函数查出结果
SELECT * from  class where classid in (SELECT a.ban FROM class a,class b where a.banji=b.classid)  and banji=0