根据id查所有父级或子级

查询子级 使用存储过程

delimiter //

drop PROCEDURE IF EXISTS  showChildLst//

CREATE PROCEDURE showChildLst (IN rootid INT)
BEGIN
 DECLARE Level int ;
 drop TABLE IF EXISTS tmpLst;
 CREATE TABLE tmpLst (
  id int,
  nLevel int,
  sCort varchar(8000)
 );
 
 Set Level=0 ;
 INSERT into tmpLst SELECT id,Level,ID FROM crm_presona_dk WHERE presona_pid=rootid;
 WHILE ROW_COUNT()>0 DO
  SET Level=Level+1 ;
  INSERT into tmpLst 
   SELECT A.id,Level,concat(B.sCort,'-',A.id) FROM crm_presona_dk A,tmpLst B 
    WHERE  A.presona_pid=B.id AND B.nLevel=Level-1  ;
 END WHILE;
  
END;
//

delimiter ;

call showChildLst(2);
select * from tmpLst;

查询父级直接用sql

数据表的结构：
id  name    parent_id 
--------------------------- 
1   Home        0 
2   About       1 
3   Contact     1 
4   Legal       2 
5   Privacy     4 
6   Products    1 
7   Support     1 

SELECT T2.id, T2.name 
FROM ( 
    SELECT 
        @r AS _id, 
        (SELECT @r := parent_id FROM table1 WHERE id = _id) AS parent_id, 
        @l := @l + 1 AS lvl 
    FROM 
        (SELECT @r := 5, @l := 0) vars,  --查询id为5的所有上级
        table1 h 
    WHERE @r <> 0) T1 
JOIN table1 T2 
ON T1._id = T2.id 
ORDER BY T1.lvl DESC