IF OBJECT_ID('TESTAA') IS NOT NULL
 DROP TABLE TESTAA

CREATE TABLE TESTAA
(TP CHAR(1)
, STIME DATETIME
, ETIME DATETIME)
GO

INSERT INTO TESTAA (TP, STIME, ETIME)
 SELECT TP = 'C', STIME = '2008-01-09 07:20:00', ETIME = '2008-01-09 07:50:00' UNION ALL
 SELECT TP = 'C', STIME = '2008-01-05 03:40:00', ETIME = '2008-01-05 03:55:00' UNION ALL
 SELECT TP = 'C', STIME = '2008-01-05 01:25:00', ETIME = '2008-01-05 01:29:00' UNION ALL
 SELECT TP = 'O', STIME = '2008-01-04 13:20:00', ETIME = '2008-01-04 14:50:00' UNION ALL
 SELECT TP = 'O', STIME = '2008-01-03 17:20:00', ETIME = '2008-01-03 18:21:00' UNION ALL
 SELECT TP = 'T', STIME = '2008-01-02 07:20:00', ETIME = '2008-01-02 07:50:00' UNION ALL
 SELECT TP = 'T', STIME = '2008-01-02 04:12:00', ETIME = '2008-01-02 06:01:00'

SELECT
 TYPE = TP
 , CNT = CT
 , WORK_TIME = CAST(L_HH AS VARCHAR) + '시간 ' + CAST(L_MM AS VARCHAR) + '분 ' + CAST(L_SS AS VARCHAR) + '초'
 , AVG_TIME = CAST(AVG_HH AS VARCHAR) + '시간 ' + CAST(AVG_MM AS VARCHAR) + '분 ' + CAST(AVG_SS AS VARCHAR) + '초'
FROM
(
 SELECT
  TP
  , CT = COUNT(*)
  , LT = SUM(DATEDIFF(SS, STIME, ETIME)) 
  , L_HH = SUM(DATEDIFF(SS, STIME, ETIME))  / 3600
  , L_MM = (SUM(DATEDIFF(SS, STIME, ETIME)) % 3600 ) / 60
  , L_SS = ((SUM(DATEDIFF(SS, STIME, ETIME)) % 3600 ) % 60) / 60
  , AVG_LT = AVG(DATEDIFF(SS, STIME, ETIME))
  , AVG_HH = AVG(DATEDIFF(SS, STIME, ETIME)) / 3600
  , AVG_MM = (AVG(DATEDIFF(SS, STIME, ETIME)) % 3600) / 60
  , AVG_SS = ((AVG(DATEDIFF(SS, STIME, ETIME)) % 3600) % 60) / 60
 FROM
  TESTAA
 GROUP BY TP
) Q