Hi Gurus,
I have below query with UNION. it scan same table twice. just wondering if it is possible to re-write without union

WITH T
     AS (SELECT 'AAA' AS DESCR, 100 AS AMT FROM DUAL
         UNION ALL
         SELECT 'BBB', 200 FROM DUAL
         UNION ALL
         SELECT 'BBB', 100 FROM DUAL
         UNION ALL
         SELECT 'BBB', 300 FROM DUAL
         UNION ALL
         SELECT 'CCC', 444 FROM DUAL
         UNION ALL
         SELECT 'CCC', 333 FROM DUAL
         UNION ALL
         SELECT 'DDD', 230 FROM DUAL
         UNION ALL
         SELECT 'DDD', 240 FROM DUAL
         UNION ALL
         SELECT 'EEE', 140 FROM DUAL)
  SELECT CASE WHEN DESCR IN ('BBB', 'CCC', 'DDD') THEN 'PER_NER' ELSE 'BIZ_NER' END AS DES, SUM (AMT)
    FROM T
   WHERE DESCR <> 'AAA'
GROUP BY CASE WHEN DESCR IN ('BBB', 'CCC', 'DDD') THEN 'PER_NER' ELSE 'BIZ_NER' END
UNION ALL
  SELECT DESCR, SUM (AMT)
    FROM T
GROUP BY DESCR;

WITH T
     AS (SELECT 'AAA' AS DESCR, 100 AS AMT FROM DUAL
         UNION ALL
         SELECT 'BBB', 200 FROM DUAL
         UNION ALL
         SELECT 'BBB', 100 FROM DUAL
         UNION ALL
         SELECT 'BBB', 300 FROM DUAL
         UNION ALL
         SELECT 'CCC', 444 FROM DUAL
         UNION ALL
         SELECT 'CCC', 333 FROM DUAL
         UNION ALL
         SELECT 'DDD', 230 FROM DUAL
         UNION ALL
         SELECT 'DDD', 240 FROM DUAL
         UNION ALL
         SELECT 'EEE', 140 FROM DUAL)
  SELECT descr, SUM (AMT)
    FROM T
GROUP BY GROUPING SETS (
             (CASE
                  WHEN DESCR IN ('BBB', 'CCC', 'DDD') THEN 'PER_NER'
                  WHEN  DESCR <> 'AAA' THEN'BIZ_NER'
              END) ,
             DESCR)

I tried to use grouping set like below, but I am not able to fix these two issues: as you can see, 1. the underlined record is extra (need to be removed) ; 2, the column name missed for these two record which is case statement in grouping set.
Is it possible to re-write the query without union?
thanks in advance.

the output like below:
DESCR SUM(AMT)
100
1847
140
CCC 777
DDD 470
EEE 140
BBB 600
AAA 100

expected result is:
DES SUM(AMT)
PER_NER 1847
BIZ_NER 140
CCC 777
DDD 470
EEE 140
BBB 600
AAA 100

WITH T AS (
  SELECT 'AAA' AS DESCR, 100 AS AMT FROM DUAL
  UNION ALL
  SELECT 'BBB', 200 FROM DUAL
  UNION ALL
  SELECT 'BBB', 100 FROM DUAL
  UNION ALL
  SELECT 'BBB', 300 FROM DUAL
  UNION ALL
  SELECT 'CCC', 444 FROM DUAL
  UNION ALL
  SELECT 'CCC', 333 FROM DUAL
  UNION ALL
  SELECT 'DDD', 230 FROM DUAL
  UNION ALL
  SELECT 'DDD', 240 FROM DUAL
  UNION ALL
  SELECT 'EEE', 140 FROM DUAL
), grps as (
  SELECT COALESCE ( 
           descr,
           CASE
             WHEN DESCR IN ('BBB', 'CCC', 'DDD') THEN 'PER_NER'
             WHEN DESCR <> 'AAA' THEN'BIZ_NER'
           END
         ) descr,
         SUM (AMT)
    FROM T
GROUP BY GROUPING SETS (
             (CASE
                  WHEN DESCR IN ('BBB', 'CCC', 'DDD') THEN 'PER_NER'
                  WHEN  DESCR <> 'AAA' THEN'BIZ_NER'
              END) ,
             DESCR)
)
  SELECT * FROM grps
  WHERE  descr IS NOT NULL;
  
DESCR         SUM(AMT)   
EEE                140 
DDD                470 
AAA                100 
CCC                777 
BBB                600 
PER_NER           1847 
BIZ_NER            140