Question

"id"    "parent"    "name"
"1"     "0"         "Books"
"2"     "1"         "Crime Fiction"
"3"     "2"         "Death On the Nile"

从上述内容中，我如何选择父行的name以及child的名称。这里，将提供子行的名称。我需要得到父母的name。

期望的输出：

@id = 3

Crime Fiction //This is the name of the parent row - in this case 2
     Death on the Nile // This is the name of the row who's id was supplied.

如何在同一张桌子内进行选择？

Answer 1

select parent.name, child.name
from your_table child
left join your_table parent on child.parent = parent.id
where child.id = 3

Answer 2

select t1.name, t2.name as parent_name from tablename t1 join tablename t2
on t1.id=t2.parent where t1.id=3

Answer 3

SELECT (CASE WHEN p.name IS NULL THEN "???" ELSE p.name END) AS name 
FROM <your_table> c LEFT JOIN <your_table> p
ON c.parent = p.id
WHERE c.name = <yourname>
LIMIT 1;

此查询将返回给定子名称的父名称，或“???”如果找不到父母。

提供子行时，从同一个表中选择父行

3 个答案: