mysql從子類id查詢所有父類

表結構

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 

 

mysql代碼如下：

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 <> 0) T1 JOIN table1 T2 ON T1._id = T2.id ORDER BY T1.lvl DESC 

 

代碼@r := 5標示查詢id爲5的所有父類。結果如下

1, 'Home' 2, 'About' 4, 'Legal' 5, 'Privacy'