关键词：mysql树查询，mysql递归查询
转自：http://www.cnblogs.com/c-h-y/p/9420726.html
之前一直用的是Oracle，对于树形查询可以使用start with ... connect by
select * from menu start with id='130000' connect by id = prior parent_id;
没错，这是Oracle所支持的
现在公司用的是mysql，对于这种查询方式只能通过sql语句实现了
语言都是相通的，何况sql呢
mysql随没有自带的语法支持，不过可以通过创建函数来实现递归查询。
直接上sql语句
create table `nodelist` (
`id` int (11),
`nodecontent` varchar (300),
`pid` int (11)
);
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('1','a',NULL);
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('2','b','1');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('3','c','1');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('4','d','2');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('5','e','3');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('6','f','3');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('7','g','5');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('8','h','7');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('9','i','8');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('10','j','8');
之后创建一个函数
--根据父节点求出所有儿子节点 delimiter $$ DROP FUNCTION IF EXISTS `getChild`$$ CREATE DEFINER=`root`@`localhost` FUNCTION `getChild`(rootId INT) RETURNS VARCHAR(1000) CHARSET utf8 BEGIN DECLARE ptemp VARCHAR(1000); DECLARE ctemp VARCHAR(1000); SET ptemp = '#'; SET ctemp =CAST(rootId AS CHAR); WHILE ctemp IS NOT NULL DO SET ptemp = CONCAT(ptemp,',',ctemp); SELECT GROUP_CONCAT(id) INTO ctemp FROM nodelist WHERE FIND_IN_SET(pid,ctemp)>0; END WHILE; END$$ DELIMITER ; 如果报错： 错误：This function has none of DETERMINISTIC, NO SQL, or READS SQL DATA in its de 解决：set global log_bin_trust_function_creators=TRUE; 这是我们开启了bin-log, 我们就必须指定我们的函数是否是 1 DETERMINISTIC 不确定的 2 NO SQL 没有SQl语句，当然也不会修改数据 3 READS SQL DATA 只是读取数据，当然也不会修改数据 4 MODIFIES SQL DATA 要修改数据 5 CONTAINS SQL 包含了SQL语句 其中在function里面，只有 DETERMINISTIC, NO SQL 和 READS SQL DATA 被支持。如果我们开启了 bin-log, 我们就必须为我们的function指定一个参数。 在MySQL中创建函数时出现这种错误的解决方法： set global log_bin_trust_function_creators=TRUE;
-- 测试使用
SELECT * FROM nodelist WHERE FIND_IN_SET(id, getChild(3))
-- 根据该节点获取所有父节点 delimiter $$ DROP FUNCTION IF EXISTS `getParentId`$$ CREATE DEFINER=`test1`@`localhost` FUNCTION `getParentId`(rootId INT) RETURNS VARCHAR(1000) CHARSET utf8 BEGIN DECLARE ptemp VARCHAR(1000); DECLARE ctemp VARCHAR(1000); SET ptemp = '#'; SET ctemp =CAST(rootId AS CHAR); WHILE ctemp IS NOT NULL DO SET ptemp = CONCAT(ptemp,',',ctemp); SELECT GROUP_CONCAT(pid) INTO ctemp FROM nodelist WHERE FIND_IN_SET(id,ctemp)>0; END WHILE; return ptemp; END$$ DELIMITER ; -- 测试实用 SELECT * FROM nodelist WHERE FIND_IN_SET(id, getParentId(3))
-- 获取该节点相关的所有父节点子节点 delimiter $$ DROP FUNCTION IF EXISTS `getAllNode`$$ CREATE DEFINER=`test1`@`localhost` FUNCTION `getAllNode`(rootId INT) RETURNS VARCHAR(1000) CHARSET utf8 BEGIN DECLARE ptemp VARCHAR(1000); DECLARE ctemp VARCHAR(1000); SET ptemp = '#'; SET ctemp =CAST(rootId AS CHAR); WHILE ctemp IS NOT NULL DO SET ptemp = CONCAT(ptemp,',',ctemp); SELECT GROUP_CONCAT(id) INTO ctemp FROM nodelist WHERE FIND_IN_SET(pid,ctemp)>0; END WHILE; SET ctemp =CAST(rootId AS CHAR); WHILE ctemp IS NOT NULL DO SET ptemp = CONCAT(ptemp,',',ctemp); SELECT GROUP_CONCAT(pid) INTO ctemp FROM nodelist WHERE FIND_IN_SET(id,ctemp)>0; END WHILE; return ptemp; END$$ DELIMITER ; -- 测试验证 SELECT * FROM nodelist WHERE FIND_IN_SET(id, getAllNode(3))
上面难度相对比较大，再补充一个简单的自连接查询
SELECT t1.id,t1.nodecontent,t2.nodecontent parentnodecontent FROM nodelist t1 LEFT JOIN nodelist t2 ON t1.pid = t2.id
可以了。
其他相关参考：
本例根据上述代码实现（但仅限非常正序的情况，否则会出问题）
--顺序查找所有子节点 select * from ( select *,if(find_in_set(pid,@p)>0,@p:=concat(@p,',',id),0) as childId from (select * from nodelist order by id) t1 ,(select @p:=3) t2 ) t where t.childId!=0;--倒序查找所有父节点 select * from ( select *,if(find_in_set(id,@p1)>0,@p1:=concat(@p1,',',pid),0) as childId,@p1 from (select * from nodelist order by id desc ) t1 ,(select @p1:=3) t2 ) t where t.childId!=0;
借鉴 https://www.jianshu.com/p/f99665266bb1
里面用到的内置函数 https://baijiahao.baidu.com/s?id=1595349117525189591&wfr=spider&for=pc
你只要能想到的，都有对应的解决方式，幸运的是你该踩得一些坑别人实现给你填好了。