Assuming I've understood what you want, then something like this: -

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;

That's based on the following sample data, since you chose not to supply any: -

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);