在sql server中生成序列 [英] Generating a sequence in sql server

问题描述

我正在处理一个函数，它会将一个较小的数字和一个较大的数字作为参数，并返回一个包含（包括）之间的所有内容的表。

I am working on a function that will take a low number and a high number as paramaters and returns a table containing everything between (and including).

我可以使用一个游标，并增加一个变量，将它添加到基于作用域的表每次迭代，但我更喜欢避免游标，如果可能的话。有没有人有一个建议的方法来做到这一点？

I know I could use a cursor and increment a variable adding it to a scope based table every iteration, but I would prefer to avoid a cursor if possible. Does anyone else have a suggestion for a way to do this? (As i'm typing this im thinking possibly a CTE, which I will go investigate).

推荐答案

只需创建一个索引的永久辅助数字表，并用它做。这将执行任何其他方法。

Just create an indexed permanent auxiliary numbers table and be done with it. This will out perform any other method.

有关更多详细信息，请参阅Jeff Moden的答案和用于填充此表的脚本。如果由于某种原因不是一个选项，这应该根据链接答案中的性能测试击败递归CTE。

See Jeff Moden's answer here for more details and a script to populate such a table. if for some reason that isn't an option this should beat the recursive CTE according to the performance tests in the linked answer.

   WITH E00(N) AS (SELECT 1 UNION ALL SELECT 1),
        E02(N) AS (SELECT 1 FROM E00 a, E00 b),
        E04(N) AS (SELECT 1 FROM E02 a, E02 b),
        E08(N) AS (SELECT 1 FROM E04 a, E04 b),
        E16(N) AS (SELECT 1 FROM E08 a, E08 b),
        E32(N) AS (SELECT 1 FROM E16 a, E16 b),
   cteTally(N) AS (SELECT ROW_NUMBER() OVER (ORDER BY N) FROM E32)
   SELECT N FROM cteTally
   WHERE N BETWEEN 10 AND 20

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