oracle遞歸查詢語句（oracle遞歸查詢函數）

眾所周知，目前的mysql版本中并不支持直接的遞歸查詢，但是通過遞歸到迭代轉化的思路，還是可以在一句SQL內實現樹的遞歸查詢的。這個得益于Mysql允許在SQL語句內使用@變量。以下是示例代碼。

創建表格

CREATE TABLE `lf_ctrl_trade` (
    `TRADEID` int , -- 節點ID
    `nodename` varchar (60), -- 節點名稱
    `PARENTID` int  -- 節點父ID
); 

方案一：

 SELECT TRADEID AS ID,PARENTID AS 父ID ,levels AS 父到子之間級數, paths AS 父到子路徑 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：

創建函數

DROP FUNCTION IF EXISTS queryChildrenTrade;

CREATE FUNCTION `queryChildrenTrade` (myid INT)

RETURNS VARCHAR(4000)

BEGIN

DECLARE sTemp VARCHAR(4000);

DECLARE sTempChd VARCHAR(4000);

 

SET sTemp = '$';

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;

如何查詢：

select * from lf_ctrl_trade where FIND_IN_SET(TRADEID, queryChildrenTrade(3000))