(资料图片仅供参考)

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))