Question

有没有办法从SQL中的一列顺序选择值对？

即。如果我有一个包含一列数字的表

SomeID
------
1
2
3
5
7
11

我需要像这样返回一组两列：

FirstID    SecondID
-------------------
1          2
2          3
3          5
5          7
7          11

可以这样做吗？

编辑：

我应该提到，第一个结果集的顺序很重要，可能不是顺序的。

即。可能是

SomeID    
5
3
9
8
...

FirstID    SecondID
5          3
3          9
9          8
...        ...

Answer 1

您可以使用窗口函数LEAD（或LAG）

执行此操作

;WITH My_CTE AS
(
SELECT
    some_id as first_id,
    LEAD(some_id, 1, NULL) OVER (ORDER BY some_id) AS second_id
FROM
    My_Table
)
SELECT
    first_id,
    second_id
FROM
    My_CTE
WHERE
    second_id IS NOT NULL   -- to not get 11, NULL at the end
ORDER BY
    first_id

如果您不关心最后一行，那么您甚至可以单独使用CTE查询，而无需使用CTE。

Answer 2

SELECT 
    t1.SomeID as FirstID,
    t2.SomeID as SecondID
FROM
(
    SELECT SomeID, ROW_NUMBER()OVER(ORDER BY SomeID) as Inc
    FROM TABLE
) t1
LEFT JOIN
(
    SELECT SomeID, ROW_NUMBER()OVER(ORDER BY SomeID)-1 as Inc
    FROM TABLE
) t2 ON t2.Inc = t1.Inc

适用于sql server＆gt; = 2005

Answer 3

简单来说，使用相关的子查询返回以下值：

select t1.id as FirstID, (select min(t2.id) from tablename t2
                          where t2.id > t1.id) as SecondID
from tablename
where t1.id < (select max(id) from tablename)

Answer 4

简单地左键连接表格本身，如 -

Select a.somecol,b.somecol
From TableA as a
Left join TableA as b
On b.someid = a.someid + 1
Where b.someid is not null

Answer 5

试试这个

declare @t table( SomeID int) insert into @t (SomeID) values
(5),(3),(9),(8)


;with t as(Select someid,row_number() over (order by (select 1)) as  rn 
from @t)        
        Select a.someid,b.someid
        From t as a
        Left join t as b
        On b.rn = a.rn + 1
        Where b.someid is not null

SQL Server - 从一列

5 个答案: