mysql 递归查询

CREATE TABLE nodelist(  
     id INT PRIMARY KEY,            
     nodename VARCHAR(20),          
     pid INT                         
    );     



    Insert INTO nodelist VALUES(1,'A',null);  //父节点为，即根节点。
    Insert INTO nodelist VALUES(2,'B',1);  
    Insert INTO nodelist VALUES(3,'C',1);  
    Insert INTO nodelist VALUES(4,'D',2);  
    Insert INTO nodelist VALUES(5,'E',3);  
    Insert INTO nodelist VALUES(6,'F',3);  
    Insert INTO nodelist VALUES(7,'G',5);  
    Insert INTO nodelist VALUES(8,'H',7);  
    Insert INTO nodelist VALUES(9,'I',8);  
    Insert INTO nodelist VALUES(10,'J',8); 

CREATE FUNCTION `getChildList`(rootId INT) //rootId为你要查询的节点。
     RETURNS VARCHAR(1000)  
     BEGIN 
       DECLARE pTemp VARCHAR(1000);  
       DECLARE cTemp VARCHAR(1000);  //两个临时变量
      
       SET pTemp = '$';  
       SET cTemp =cast(rootId as CHAR);  //把rootId强制转换为字符。
      
       WHILE cTemp is not null DO  
         SET pTemp = concat(pTemp,',',cTemp);  //把所有节点连接成字符串。
         SELECT group_concat(id) INTO cTemp FROM nodelist   
         WHERE FIND_IN_SET(pid,cTemp)>0; 
                // FIND_IN_SET(str,strlist)的方法网上大把不解释。
       END WHILE;  
       RETURN pTemp;  
     END 

      

select  getChildList(5)

select * from nodelist t where  FIND_IN_SET(id, getChildList(3));