mysql递归查询从子类ID查询所有父类

先来看数据表的结构如下：


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 
我要的要求是根据一个分类ID（这个分类ID可能是一个子分类），得到所有的父分类，下面是相应的SQL：

 

方式一：

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,
        table1 h
    WHERE  @r <> 2
    union  all  select  @r, parent_id,@l+1  FROM  table1  WHERE  id = @r
    ) T1
JOIN  table1 T2
ON  T1._id = T2.id
ORDER  BY  T1.lvl  DESC

 方式二：

SELECT  T2.id, T2. name
FROM  (
    SELECT
        @r  AS  _id,
        @stop:=@stop+if(@r=2,1,@stop)  as  stop,
        ( SELECT  @r := parent_id  FROM  table1  WHERE  id = _id)  AS  parent_id,
        @l := @l + 1  AS  lvl
    FROM
        ( SELECT  @r := 5, @l := 0, @stop:=0) vars,
        table1 h
    WHERE  @stop < 1) T1
JOIN  table1 T2
ON  T1._id = T2.id
ORDER  BY  T1.lvl  DESC

 

转载于:https://www.cnblogs.com/interdrp/p/8045999.html