Question

我希望能够查询MySQL数据库，以便根据父母和孩子找到一个人的兄弟姐妹。我们假设在这里假设一个人的父母的孩子，以及一个人的孩子的父母是该人的兄弟姐妹。

人

id  name
-----------
1   jonny
2   tom
3   sally
4   bill
5   katie
6   jessica

RELS

id  parent  child
--------------------
1   2       3
2   5       6
3   2       1
4   1       6
5   1       4
6   6       2

我一直在试图弄清楚如何以一种给我这些结果的方式加入这两个表，但我无法做到。

SELECT people.id,people.name FROM people, rels
INNER JOIN rels children ON people.id = rels.parent
INNER JOIN rels siblings ON children.id = siblings.child
WHERE children.child = '1'

Answer 1

试试这个

   SELECT people.id,people.name  FROM people
   LEFT JOIN rels children ON people.id = children.parent
   LEFT JOIN rels siblings ON people.id = siblings.child
   WHERE children.child = '1'
   group by people.id

DEMO HERE

Answer 2

我已经提出了一个使用UNIONs的解决方案，我认为现在这样做。如果有人能想出一个纯粹基于JOIN的解决方案，我很乐意看到它！

SELECT people.*,c.* FROM rels
   INNER JOIN rels c ON rels.parent = c.parent
   INNER JOIN people ON people.id = c.child
   WHERE rels.child = '1' AND people.id <> '1'

UNION

SELECT people.*,p.* FROM rels
   INNER JOIN rels p ON rels.child = p.child
   INNER JOIN people ON people.id = p.parent
   WHERE rels.parent = '1' AND people.id <> '1'

http://sqlfiddle.com/#!2/45ba3/103/0

Answer 3

我没有对此进行测试，但这应该可行：

SELECT ppl.* from people as ppl
INNER JOIN rels AS par1 on ppl.id = par1.child
INNER JOIN rels as par2 on par2.parent = par1.parent
INNER JOIN people as sib on sib.id = par2.child
WHERE ppl.id = '3'

以sally（id = 3）

为例进行说明

从PPL中选择要找到兄弟姐妹的人。（id = 3）

从PAR1（父级）中选择其父级。选择父= 2

从PAR2（父）选择相同的父选择父= 2

从SIB（人员）中选择id = 3,1

的详细信息

如果这不起作用，请告诉我......

MySQL INNER JOIN与WHERE条件的结果？

3 个答案: