Comparing values of a column in a group

Question

Hi All,
i have key, dt, col1
1, dt1, a
1, dt2, b
2, dt1, a
2, dt2, a
2, dt3, a
i need to check whether all values of col1, for column key is same or different.
in the example key 1 has difft values for col1,
key 2 has same values for col1.
how can i achieve this in a single sql query?
thanks in advance

Answer 1

SQL> with virtual_tab as
  2  (select 1 key, 'dt1' dt, 'a' col1 from dual
  3   union all
  4   select 1 key, 'dt2' dt, 'b' col1 from dual
  5   union all
  6   select 2 key, 'dt1' dt, 'a' col1 from dual
  7   union all
  8   select 2 key, 'dt2' dt, 'a' col1 from dual
  9   union all
10   select 2 key, 'dt3' dt, 'a' col1 from dual)
11  select * from virtual_tab;
       KEY DT  C
         1 dt1 a
         1 dt2 b
         2 dt1 a
         2 dt2 a
         2 dt3 a
SQL> with virtual_tab as
  2  (select 1 key, 'dt1' dt, 'a' col1 from dual
  3   union all
  4   select 1 key, 'dt2' dt, 'b' col1 from dual
  5   union all
  6   select 2 key, 'dt1' dt, 'a' col1 from dual
  7   union all
  8   select 2 key, 'dt2' dt, 'a' col1 from dual
  9   union all
10   select 2 key, 'dt3' dt, 'a' col1 from dual)
11  select vt2.key,
12         case when vt2.cnt = 1 then
13                'different'
14              else
15                'the same'
16         end as remarks
17    from (select vt1.key,
18                 vt1.dt,
19                 vt1.col1,
20                 count(*) over (partition by key, col1 order by key, col1) cnt
21            from virtual_tab vt1) vt2
22  group by vt2.key, vt2.cnt;
       KEY REMARKS
         1 different
         2 the same
SQL>