oracle递归查询语句（oracle递归查询函数）

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 ,'|') pathallFROM lf_ctrl_trade,(SELECT @le:=0,@pathlevel:='', @pathall:='',@pathnodes:='') vvORDER 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))