前言：
最近面试的时候遇到公司要求只能用SQL来查询无限极的数据，不能用PHP程序做递归查询，现在分享方法。
下面给出一个function来完成的方法
下面是sql脚本，想要运行的直接赋值粘贴进数据库即可。
-- ---------------------------- -- 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');
把下面的语句直接粘贴进命令行执行即可（注意修改传入的参数，默认rootId，表明默认treenodes）
根据传入id查询所有父节点的id
方法1:
级数不知道，可以用类似下面这个语句查询, @r := 6为查询条件
SELECT T2.id, T2.nodename, T2.pid FROM ( SELECT @r AS _id, (SELECT @r := pid FROM treenodes WHERE id = _id) AS pid, @l := @l + 1 AS l FROM (SELECT @r := 6, @l := 0) vars, treenodes h WHERE @r != 0) T1 JOIN treenodes T2 ON T1._id = T2.id ORDER BY T1.l;
结果:
方法2:
delimiter // CREATE FUNCTION `getParList`(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 //
执行命令
select * from treenodes where FIND_IN_SET(id,getParList(15));
结果：
根据传入id查询所有子节点的id
delimiter // CREATE FUNCTION `getChildList`(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 //
执行命令
select * from treenodes where FIND_IN_SET(id,getChildList(7));
结果：
