SQL> select bureau_id,
  2         count(1) as all_counts,
  3         sum(decode(field1,'A',1,0)) as A_counts
  4    from tableA tt
  5   group by bureau_id;

 BUREAU_ID ALL_COUNTS   A_COUNTS
---------- ---------- ----------
       100          3          2
       101          4          3

------解决方案--------------------

try it ..

SQL code

SQL>  select *
  2     from tableA tt;

 BUREAU_ID FIELD1     FIELD2     FIELD3
---------- ------ ---------- ----------
       100 A               1          2
       100 A               3          2
       100 B               7          5
       101 A               2          3
       101 B               6          6
       101 A              11          9
       101 A              17          8

7 rows selected

SQL> 
SQL> select bureau_id,
  2         count(1) as all_counts,
  3         sum(decode(field1,'A',1,0)) as a_counts,
  4         sum(decode(sign(field2-field3),1,1,0)) as field2_large_than_field3
  5    from tableA tt
  6   group by bureau_id;

 BUREAU_ID ALL_COUNTS   A_COUNTS FIELD2_LARGE_THAN_FIELD3
---------- ---------- ---------- ------------------------
       100          3          2                        2
       101          4          3                        2

SQL>