众所周知，目前的mysql版本中并不支持直接的递归查询，但是通过递归到迭代转化的思路，还是可以在一句SQL内实现树的递归查询的。这个得益于Mysql允许在SQL语句内使用@变量。以下是示例代码。
创建表格
CREATE TABLE `lf_ctrl_trade` ( `TRADEID` int , -- 节点ID `nodename` varchar (60), -- 节点名称 `PARENTID` int -- 节点父ID); 方案一：
SELECT TRADEID AS ID,PARENTID AS 父ID ,levels AS 父到子之间级数, paths AS 父到子路径 FROM ( SELECT TRADEID,PARENTID, @le:= IF (PARENTID = 0 ,0, IF( LOCATE( CONCAT(\'|\',PARENTID,\':\'),@pathlevel) > 0 , SUBSTRING_INDEX( SUBSTRING_INDEX(@pathlevel,CONCAT(\'|\',PARENTID,\':\'),-1),\'|\',1) +1 ,@le+1) ) levels , @pathlevel:= CONCAT(@pathlevel,\'|\',TRADEID,\':\', @le ,\'|\') pathlevel , @pathnodes:= IF( PARENTID =0,\',0\', CONCAT_WS(\',\', IF( LOCATE( CONCAT(\'|\',PARENTID,\':\'),@pathall) > 0 , SUBSTRING_INDEX( SUBSTRING_INDEX(@pathall,CONCAT(\'|\',PARENTID,\':\'),-1),\'|\',1) ,@pathnodes ) ,PARENTID ) )paths ,@pathall:=CONCAT(@pathall,\'|\',TRADEID,\':\', @pathnodes ,\'|\') pathall FROM lf_ctrl_trade, (SELECT @le:=0,@pathlevel:=\'\', @pathall:=\'\',@pathnodes:=\'\') vv ORDER BY PARENTID,TRADEID ) srcORDER BY TRADEID方案二：
创建函数
DROP FUNCTION IF EXISTS queryChildrenTrade;CREATE FUNCTION `queryChildrenTrade` (myid INT)RETURNS VARCHAR(4000)BEGINDECLARE sTemp VARCHAR(4000);DECLARE sTempChd VARCHAR(4000); SET sTemp = \'$\';SET sTempChd = cast(myid as char); WHILE sTempChd is not NULL DOSET sTemp = CONCAT(sTemp,\',\',sTempChd);SELECT group_concat(TRADEID) INTO sTempChd FROM lf_ctrl_trade where FIND_IN_SET(PARENTID,sTempChd)>0;END WHILE;return sTemp;END;如何查询：
select * from lf_ctrl_trade where FIND_IN_SET(TRADEID, queryChildrenTrade(3000))
