Fibonacci Series,Factorial in SQL Server using CTE Recursion

-- Factorial

;with fact as (
    select 1 as fac, 1 as num
    union all
    select fac*(num+1), num+1
    from fact
    where num<12)
select fac
from fact
where num=5

-- Fibonacci Series

;with fibo as (
    select 0 as fibA, 0 as fibB, 1 as seed, 1 as  num
    union all
    select seed+fibA, fibA+fibB, fibA, num+1
    from fibo
    where num<12)
select fibA
from fibo

-- Number Sequence: 1 to 10

;with num_seq as (
    select 1 as num
    union all
    select num+1
    from num_seq
    where num<100)
select num
from num_seq
where num < 10

-- Date Sequence: May 2011

;with dt_seq as (
    select cast('5/1/2011' as datetime) as dt, 1 as num
    union all
    select dt+1, num+1
    from dt_seq
    where num<31)
select dt
from dt_seq



for more details http://msdn.microsoft.com/en-us/library/ms190766.aspx
                          http://sqlwithmanoj.com/2011/05/23/cte-recursion-sequence-dates-factorial-fibonacci-series/