Question

我在谈论SQL Server 2008.我有三个nvarchar列的表。我想在第N行选择第一列，从第M行选择第二列，从第K行选择第三列，其中M，N，K不相等。

如何编写这样的查询？也可以选择随机行吗？

Answer 1

您可以使用具有ROW_NUMBER()功能的CTE来实现此目的：

;WITH CTE AS
(
   SELECT 
      Column1, Column2, Column3,
      (your list of additional columns - if needed),
      RN = ROW_NUMBER() OVER (ORDER BY InsertionDate)
)
SELECT 
    FirstValue = (SELECT Column1 FROM CTE WHERE RN = N),
    SecondValue = (SELECT Column2 FROM CTE WHERE RN = M),
    ThirdValue = (SELECT Column3 FROM CTE WHERE RN = K)

您需要在此查询中将N, M, K替换为实际的整数值 - 或者定义SQL变量以保存这三个值。

Answer 2

declare @i1 int;
declare @i2 int;
declare @i3 int;
SET @i1=2;
SET @i2=4;
SET @i3=1;

;with t1 as
(
select *,row_number() over(order by (select 0)) as rn  from t
)
 select max(CASE rn WHEN @i1 then N1 else '' end),
        max(CASE rn WHEN @i2 then N2 else '' end),
        max(CASE rn WHEN @i3 then N3 else '' end)
        from t1 where rn in (@i1,@i2,@i3);

在数据库表中选择第n列

2 个答案: