말일에 근무 했는지 여부를 알수가 없는데;; 

결과를 어떡해 뽑을 수 있는지 의문이네요;;

일 시작한 날과 끝나는 날만 존재하는데;;

달력 테이블을 만드시고 비교하세요.

(또는 매월 말일만 들어있는 테이블을 만드셔서 활용)

SET NOCOUNT ON

DECLARE @MM INT

DECLARE @I INT

DECLARE @Tmp TABLE ( NUM INT )

SELECT @MM = 12, @I = 0

WHILE ( @I < @MM )

BEGIN

 INSERT INTO @Tmp VALUES ( @I )

 SET @I = @I + 1

END 

WITH TEST AS (

    SELECT 'emp1' AS USERID, '20120115' AS StartDate, '20121030' AS EndDate

)

, CAL AS (

    SELECT NUM, CONVERT(CHAR(8), DATEADD(D, -1, DATEADD(M, NUM, '20120201')), 112) AS LastDay

      FROM @Tmp A

)   

SELECT LEFT(A.LastDay, 6) AS MM

       , CASE WHEN B.USERID IS NULL THEN '0' ELSE '1' END 

  FROM CAL A 

       LEFT OUTER JOIN TEST B ON A.LastDay BETWEEN B.StartDate AND B.EndDate

declare @s_dt varchar(8) , @e_dt varchar(8)

set @s_dt = '20120115'

set @e_dt = '20121030' ;

with res

as (

   select convert(varchar(8) , dateadd(dd,-1,dateadd(mm,  number + 1, left(@s_dt,4) +'0101' )) ,112) lastdate

     from master.dbo.spt_values

    where type ='P'

      and number < 12  )

select  *

  from ( select substring(lastdate,3,4) mon

             , (case when lastdate between @s_dt and @e_dt then 1 else 0 end ) gb

           from res   ) as p

  pivot

  (

    sum( p.gb)

    for p.mon in  ( [1201],[1202],[1203],[1204],[1205],[1206],[1207],[1208],[1209],[1210],[1211],[1212] )

  ) as pvt