Generating a sequence in sql server

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).

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).

Martin Smith

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

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

Yes, you can use a recursive CTE to do this. For example to generate numbers between 10 and 20 inclusive:

WITH f AS
(
    SELECT 10 AS x
    UNION ALL
    SELECT x + 1 FROM f WHERE x < 20
)
SELECT * FROM f

来源：https://stackoverflow.com/questions/5279071/generating-a-sequence-in-sql-server

标签

sql-server-2005

cursor

Sequence