자문 자답 입니다. ^^

WITH TEMP1 AS (

SELECT 1 NUM, 'AAA' P_CTG_CODE, 'AAA-111' CTG_DESC FROM DUAL

UNION ALL SELECT 2, 'AAA', 'AAA-111' FROM DUAL

UNION ALL SELECT 3, 'AAA', 'AAA-111' FROM DUAL

UNION ALL SELECT 4, 'BBB', 'BBB-111' FROM DUAL

UNION ALL SELECT 5, 'CCC', 'CCC-111' FROM DUAL

UNION ALL SELECT 6, 'CCC', 'CCC-111' FROM DUAL

UNION ALL SELECT 7, 'AAA', 'AAA-111' FROM DUAL

UNION ALL SELECT 8, 'AAA', 'AAA-111' FROM DUAL

UNION ALL SELECT 9, 'CCC', 'CCC-111' FROM DUAL

UNION ALL SELECT 10, 'CCC', 'CCC-111' FROM DUAL

UNION ALL SELECT 11, 'BBB', 'BBB-111' FROM DUAL

UNION ALL SELECT 12, 'BBB', 'BBB-111' FROM DUAL

),

TEMP2 AS (

SELECT

(

CASE

WHEN NUM = 1 OR CTG_DESC != (LAG(CTG_DESC, 1, NULL) OVER(ORDER BY NUM)) THEN

1

ELSE

NULL

END

) CNUM,

A.*

FROM TEMP1 A

),

TEMP3 AS (

SELECT

COUNT(DECODE(CNUM, 1, 1)) OVER(ORDER BY NUM) GRP,

A.*

FROM TEMP2 A

)

SELECT

COUNT(*) OVER(PARTITION BY GRP) CNT,

A.*

FROM TEMP3 A

SELECT num, p_ctg_code, ctg_desc
     , grp
     , COUNT(*) OVER(PARTITION BY grp) cnt
  FROM (SELECT num, p_ctg_code, ctg_desc
             , COUNT(flag) OVER(ORDER BY num) grp
          FROM (SELECT num, p_ctg_code, ctg_desc
                     , DECODE( p_ctg_code
                             , LAG(p_ctg_code) OVER(ORDER BY num)
                             , NULL, 1) flag
                  FROM temp
                )
        )
;