Query return value

Question

hi everybody
i join new project and here some query use in reports like this, bt i m confuse abt
ths query. that exact wht meaning of this query
plz help me
SELECT SUM(QTY),
SUM(val)
FROM (
SELECT
SUM(NVL(m.item_qty,0)) qty,
SUM(NVL(m.item_qty,0) * rate) VAL
FROM inv_m m
WHERE m.div_code = 'IND01'
AND m.inv_date BETWEEN TO_DATE('1-JAN-2006') AND TO_DATE('29-JUL-2006'))

Answer 1

It would give another result in the presence of NULLs with AVG aggregate for example.
DROP TABLE T1;
CREATE TABLE T1 AS
     SELECT
                DECODE(MOD(ROWNUM, 2), 0, OBJECT_ID, TO_NUMBER(NULL)) C1
               ,DECODE(MOD(ROWNUM, 2), 0, OBJECT_NAME, NULL) C2
          FROM USER_OBJECTS
          WHERE ROWNUM <= 10
SELECT * FROM T1;
    C1 C2
171692 ATT_EMP_LEAVES
28972 COUNTRIES
28977 DEPARTMENTS
28978 DEPT_ID_PK
28982 EMPLOYEES
10 rows selected.
COLUMN Count FOR 999
COLUMN SumC1 FOR 9999999
COLUMN MinC1 FOR 9999999
COLUMN MaxC1 FOR 9999999
COLUMN AvgC1 FOR 9999999.999
COLUMN StddevC1 FOR 9999999.999
COLUMN MinC2 FOR A15
COLUMN MaxC2 FOR A15
SELECT
           COUNT(*) Count
          ,SUM(C1)     SumC1
          ,MIN(C1)     MinC1     
          ,MAX(C1)     MaxC1
          ,AVG(C1)     AvgC1
          ,STDDEV(C1)     StddevC1
          ,MIN(C2)     MinC2
          ,MAX(C2)     MaxC2
     FROM T1;
COUNT    SUMC1    MINC1    MAXC1        AVGC1     STDDEVC1 MINC2           MAXC2
   10   287601    28972   171692    57520.200    63823.977 ATT_EMP_LEAVES  EMPLOYEES
SELECT
           COUNT(*) Count
          ,SUM(C1)     SumC1
          ,MIN(C1)     MinC1     
          ,MAX(C1)     MaxC1
          ,AVG(C1)     AvgC1
          ,STDDEV(C1)     StddevC1
          ,MIN(C2)     MinC2
          ,MAX(C2)     MaxC2
     FROM T1
     WHERE C1 IS NOT NULL
COUNT    SUMC1    MINC1    MAXC1        AVGC1     STDDEVC1 MINC2           MAXC2
    5   287601    28972   171692    57520.200    63823.977 ATT_EMP_LEAVES  EMPLOYEES
(SELECT
           SUM(C1)
          ,MIN(C1)
          ,MAX(C1)
          ,AVG(C1)
          ,STDDEV(C1)
          ,MIN(C2)
          ,MAX(C2)
     FROM T1
     WHERE C1 IS NOT NULL
MINUS
SELECT
           SUM(C1)
          ,MIN(C1)
          ,MAX(C1)
          ,AVG(C1)
          ,STDDEV(C1)
          ,MIN(C2)
          ,MAX(C2)
     FROM T1
UNION ALL
(SELECT
           SUM(C1)
          ,MIN(C1)
          ,MAX(C1)
          ,AVG(C1)
          ,STDDEV(C1)
          ,MIN(C2)
          ,MAX(C2)
     FROM T1
MINUS
SELECT
           SUM(C1)
          ,MIN(C1)
          ,MAX(C1)
          ,AVG(C1)
          ,STDDEV(C1)
          ,MIN(C2)
          ,MAX(C2)
     FROM T1
     WHERE C1 IS NOT NULL
no rows selectedCheers:o)