如何找到用於交叉的ID號碼

假設有一個稱爲堆棧的表格;如何找到用於交叉的ID號碼

Id  StackId 
------------------- 
.    . 
1    10 
2    12 
3    10 
4    10 
5    11 
11   5 
.    . 
.    .

如何學習交叉id像？

Id = 5 
StackId = 11 

Id = 11 
StackId = 5

我不能寫SQL語句，顯示我

5,11 
11,5

我不知道這些數字，因爲該表具有1.000.000+行，所以我想找到它喜歡5,11行

來源

2013-04-16 Stack User

如何顯示結果？第一個樣品或第二個樣品？ – Freelancer

你並不是真的在尋找'SELECT id，stackid FROM stack'，對嗎？ –

'select id，stackId from stack where id in（5,11)'' would give you second second（last）result – agim

您可以通過聚合方式這個問題，以及爲連接。這裏有一個方法：

select (case when id < StackId then id else StackId end) as FirstVal, 
     (case when id < StackId then StackId else id end) as SecondVal 
from t 
group by (case when id < StackId then id else StackId end), 
     (case when id < StackId then StackId else id end) 
having count(distinct id) = 2

如果你有一個least()和greatest()功能的數據庫，你知道現在有複製的表，你可以改寫這個：

select least(id, StackId) as FirstVal, greatest(id, StackId) as SecondVal 
from t 
group by least(id, StackId), greatest(id, StackId) 
having count(*) = 2

來源

2013-04-16 11:02:09

使用JOIN表本身s1.Id = s2.StackId AND s1.StackId = s2.Id條件：

SELECT s1.Id, s1.StackId 
FROM Stack s1 
JOIN Stack s2 ON s1.Id = s2.StackId AND s1.StackId = s2.Id

因爲使用了INNER JOIN（缺省情況下）行，所以不會返回對應的s2值。

來源

2013-04-16 10:55:18 MarcinJuraszek

請嘗試：

select a.* from 
    YourTable a inner join YourTable b on a.Id=b.StackId

來源

2013-04-16 10:57:18 TechDo

另一種解決方案：

select * 
from Stack s 
where exists (select 1 from Stack where Id = s.StackId and StackId = s.Id)

來源

2013-04-16 11:04:44

如何找到用於交叉的ID號碼

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