ORACLE改MYSQL后的递归实现方案

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
    ) src
ORDER BY TRADEID

方案二：

创建函数

DROP FUNCTION IF EXISTS queryChildrenTrade;

CREATE FUNCTION `queryChildrenTrade` (myid INT)

RETURNS VARCHAR(4000)

BEGIN

DECLARE sTemp VARCHAR(4000);

DECLARE sTempChd VARCHAR(4000);

 

SET sTemp = '#39;;

SET sTempChd = cast(myid as char);

 

WHILE sTempChd is not NULL DO

SET 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));