Calculation of Averages

Question

I need to be able to calculate the average difference between a total average on a single row for example
Value , AverageTotValue , Difference
2, 4, -2
4, 4, 0
6, 4, +2
preferably using Discoverer plus (although I could write a function if necessary)
Can anyone help ?

Answer 1

Hi , your query as you provided it , returns just one row , whereas mine returns three rows...so , i convert it to the following:
SQL> select value , avg_total , value-avg_total diff
  2   from
  3   (
  4   select value , (select sum(value)/count(value)
  5  from
  6  (select 2 as value from dual
  7  union all
  8  select 4 as value from dual
  9  union all
10  select 6 as value from dual)) avg_total
11  from (select 2 as value from dual
12  union all
13  select 4 as value from dual
14  union all
15  select 6 as value from dual)
16  )
17  /
     VALUE  AVG_TOTAL       DIFF
         2          4         -2
         4          4          0
         6          4          2[pre]
Now , as regards , the sql statistics...
Mine
[pre]SQL> with sample_data as (select 2 as value from dual
  2  union all
  3   select 4 as value from dual
  4   union all
  5   select 6 as value from dual )
  6   select value , avg_total , value-avg_total diff
  7   from
  8   (
  9   select value , (select sum(value)/count(value) avg_total from sample_data) avg_total
10   from sample_data
11   );
Ðñüãñáììá åêôÝëåóçò
   0      SELECT STATEMENT Optimizer=ALL_ROWS (Cost=8 Card=3 Bytes=48)
   1    0   TEMP TABLE TRANSFORMATION
   2    1     LOAD AS SELECT
   3    2       UNION-ALL
   4    3         FAST DUAL (Cost=2 Card=1)
   5    3         FAST DUAL (Cost=2 Card=1)
   6    3         FAST DUAL (Cost=2 Card=1)
   7    1     VIEW (Cost=2 Card=3 Bytes=48)
   8    7       VIEW (Cost=2 Card=3 Bytes=9)
   9    8         TABLE ACCESS (FULL) OF 'SYS_TEMP_0FD9D6608_7E7090' (
          TABLE (TEMP)) (Cost=2 Card=3 Bytes=39)
ÓôáôéóôéêÜ
          2  recursive calls
          8  db block gets
          9  consistent gets
          1  physical reads
        604  redo size
        598  bytes sent via SQL*Net to client
        508  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          3  rows processed
Yours
SQL> select value , avg_total , value-avg_total diff
  2   from
  3   (
  4   select value , (select sum(value)/count(value)  
  5  from
  6  (select 2 as value from dual
  7  union all
  8  select 4 as value from dual
  9  union all
10  select 6 as value from dual)) avg_total
11  from (select 2 as value from dual
12  union all
13  select 4 as value from dual
14  union all
15  select 6 as value from dual)
16  );
Ðñüãñáììá åêôÝëåóçò
   0      SELECT STATEMENT Optimizer=ALL_ROWS (Cost=6 Card=3 Bytes=48)
   1    0   VIEW (Cost=6 Card=3 Bytes=48)
   2    1     VIEW (Cost=6 Card=3 Bytes=9)
   3    2       UNION-ALL
   4    3         FAST DUAL (Cost=2 Card=1)
   5    3         FAST DUAL (Cost=2 Card=1)
   6    3         FAST DUAL (Cost=2 Card=1)
ÓôáôéóôéêÜ
          0  recursive calls
          0  db block gets
          0  consistent gets
          0  physical reads
          0  redo size
        598  bytes sent via SQL*Net to client
        508  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          3  rows processedCoclusion: Yours is much less costly to system and so quicker.....
I have to confess that i have not thought this format ........I have learned something today....!!!!!!
I have get accustomed to using the with clause... but i may reconsider it....!!!!!!
Thanks , a lot for your valuable remarks....(as always)...!!!!
Simon