SQL返回单个列中的所有相关行

Question

我在SQL Server中看到了对递归的引用,但我使用MySQL并要求结果在一个列中.如果我有一张关系表:

itemID1 | itemiD2
---------------
  1     |   2
  1     |   3
  4     |   5

如何在任一列中选择与单个ID相关的所有ID？例如:

1 ==> 2,3

3 ==> 1,2

我尝试了自联接,但无法在一列中获取所有相关的ID.如果有一个更好的架构,那么改变表格还为时不晚.

谢谢.

Answer 1

请尝试此查询:

select
    itemID1, group_concat(cast(itemID2 as char) separator ',')
from
(
    select itemID1, itemID2 from st where itemID1 = :ID
    union 
    select itemID2, itemID1 from st where itemID2 = :ID
    union
    select s1.itemID2, s2.itemID2 from st as s1 inner join st as s2 on s1.itemID1 = s2.itemID1
    where s1.itemID2 = :ID
    union
    select s1.itemID1, s2.itemID1 from st as s1 inner join st as s2 on s1.itemID2 = s2.itemID2
    where s1.itemID1 = :ID
) as subquery
where itemID1 <> itemID2
group by itemID1

这样,您可以选择两种方式的关系(union提供独特性)以及连接项目之间的关系(也以两种方式).