SELECT StaffId,
MIN(EntryDate) AS firstDateEntrySequence, MAX(EntryDate) AS lastDateEntrySequence,
DATEDIFF(dd,MIN(EntryDate),MAX(EntryDate))+1 AS NumberOfDaysInSequence
FROM (SELECT StaffId, EntryDate,
      DATEADD(dd, - ROW_NUMBER() OVER (PARTITION BY StaffId ORDER BY EntryDate), EntryDate)
      FROM #yourSampleData
      GROUP BY StaffId, EntryDate) a(StaffId, EntryDate, EntryGroup)
GROUP BY StaffId, EntryGroup;

IF object_id('tempdb..#yourSampleData') IS NOT NULL
BEGIN
    DROP TABLE #yourSampleData;
END;

SELECT StaffId, EntryDate
INTO #yourSampleData
FROM (VALUES(1, '2012-12-12'),(1, '2012-12-13'),(1, '2012-12-15'),
            (2, '2012-12-12'),(2, '2012-12-14'),(2, '2012-12-16')
     )a(StaffId, EntryDate);

SELECT StaffId, EntryDate
INTO #yourSampleData
FROM (SELECT 1, '2012-12-12' 
      UNION ALL SELECT 1, '2012-12-13' 
	  UNION ALL SELECT 1, '2012-12-15' 
      UNION ALL SELECT 2, '2012-12-12' 
	  UNION ALL SELECT 2, '2012-12-14' 
	  UNION ALL SELECT 2, '2012-12-16'
      )a(StaffId, EntryDate);

with TestData as (
select
    PassM,
    cast(EnterDt as datetime) EnterDt,
    ConsecutiveD
from
(values
    ('Boo K K','5/1/2012 11:55:00 PM', 1),
    ('Boo K K','5/2/2012 11:30:00 PM', 2),
    ('Boo K K','5/4/2012 10:30:00 AM', 1),
    ('LIAW S','4/30/2012 11:48:52 PM', 1),
    ('LIAW S','5/1/2012 00:11:07 AM', 2),
    ('LIAW S','5/1/2012 11:59:07 AM', 2),
    ('LIAW S','5/1/2012 4:42:02 AM', 2),
    ('LIAW S','5/2/2012 1:10:09 AM', 3),
    ('LIAW S','5/2/2012 1:43:06 AM', 3),
    ('LIAW S','5/4/2012 2:17:47 AM', 1)
)dt(PassM, EnterDt, ConsecutiveD)
)
, UniqueDts as (
select distinct
    PassM,
    dateadd(dd,datediff(dd,0,EnterDt),0) UniqEnterDt
    from
    TestData
)
, GrpDates as (
select
    PassM,
    UniqEnterDt,
    GrpDate = dateadd(dd,row_number() over (partition by PassM order by UniqEnterDt) *-1,UniqEnterDt),
    rn = row_number() over (partition by PassM order by UniqEnterDt)
from
    UniqueDts
)
,ConsecutiveDts as (
select
    PassM,
    UniqEnterDt,
    rn = row_number() over (partition by PassM, GrpDate order by UniqEnterDt)
from
    GrpDates
)
select
    td.PassM,
    td.EnterDt,
    cd.rn as CompConsecutiveD,
    td.ConsecutiveD
from
    TestData td
    inner join ConsecutiveDts cd
        on (td.PassM = cd.PassM and
            dateadd(dd,datediff(dd,0,td.EnterDt),0) = cd.UniqEnterDt);