SQL Server 获取序列的多个下一个值

Question

在 SQL Server 中，您可以像这样从序列中选择下一个值：

select next value for MY_SEQ

如果您不禁止选择要从中选择的表，则对于每一行都会输出下一个值：

select next value for MY_SEQ 
from MY_TABLE

[2020-09-08 15:47:34] 350 rows retrieved starting from 1 in 102 ms (execution: 62 ms, fetching: 40 ms)

如何为序列选择下一个 n 值？

在 Oracle 中，这看起来像这样：

select MY_SEQ.nextval
from (
         select level
         from dual
         connect by level < 10
     )

---

我尝试过这样的事情：

select top(10) next value for MY_SEQ

但结果是：

[S0001][11739] 如果设置了 ROWCOUNT 选项，或者查询包含 TOP 或 OFFSET，则无法使用 NEXT VALUE FOR 函数。

我想我可以创建一个包含 n 行的临时表并从中进行选择，但这不是一个特别优雅的解决方案。

Answer 1

我认为您正在寻找系统存储过程“sp_sequence_get_range”

要从序列中获取接下来的 10 个值，应该是这样的

DECLARE @range_first_value_output sql_variant ;  
 
EXEC sys.sp_sequence_get_range  
@sequence_name = N'MY_SEQ'  
, @range_size = 10  
, @range_first_value = @range_first_value_output OUTPUT ;  
 
SELECT @range_first_value_output AS FirstNumber;  

Answer 2

您可以在获取序列值之前提取正确的行数

DECLARE @N INT = 100;

SELECT next value FOR MY_SEQ 
FROM (
    SELECT 1 X
    FROM FN_NUMBERS(@N)
) X


CREATE FUNCTION [dbo].[FN_NUMBERS](
     @MAX INT
)
RETURNS @N TABLE (N INT NOT NULL PRIMARY KEY)  
BEGIN
     WITH
       Pass0 as (select '1' as C union all select '1'),       --2 rows
       Pass1 as (select '1' as C from Pass0 as A, Pass0 as B),--4 rows
       Pass2 as (select '1' as C from Pass1 as A, Pass1 as B),--16 rows
       Pass3 as (select '1' as C from Pass2 as A, Pass2 as B),--256 rows
       Pass4 as (select TOP (@MAX) '1' as C from Pass3 as A, Pass3 as B)    --65536 rows
       ,Tally as (select TOP (@MAX) '1' as C from Pass4 as A, Pass2 as B, Pass1 as C)  --4194304 rows
       --,Tally as (select TOP (@MAX) '1' as C from Pass4 as A, Pass3 as B)               --16777216 rows
       --,Tally as (select TOP (@MAX) '1' as C from Pass4 as A, Pass4 as B)               --4294836225 rows
     INSERT INTO @N
     SELECT TOP (@MAX) ROW_NUMBER() OVER(ORDER BY C) AS N
     FROM Tally
     RETURN
END

您可以简单地使用 sys.objects 而不是计数表

SELECT next value FOR MY_SEQ 
FROM (
    SELECT TOP (@N) 1 X
    FROM sys.objects o1, sys.objects o2, sys.objects o3
) X

Answer 3

为什么不直接用下一个值填充表变量？

declare @next_values table (next_value int)
declare @i int = 1

while @i <= 10 
begin
  insert into @next_values (next_value)
              select next value for MY_SEQ from MY_TABLE

  set @i = @i + 1
end

-- We return those values 
select * from @next_values