Simple query to find difference between 2 numbers in one column relative to another column

Question

Hello,
I want to find the difference between 2 numbers from same column corresponding to some condition of another column. How do i that?
Eg: Say I have a table with 3 columns A, B & C.
A -> Varchar2
B -> Varchar2
C -> Number
A
B
C
A
D
1
B
C
2
C
B
3
D
A
4
I want something like "value of column C corresponding to min(col A) - value of column C corresponding to min(col B) = result (number)" without having to write 2 select statements. How do I do that?
Thanks in advance
aBBy007
System notes:
2-node 11.2.0.3.4 GI/RDBMS running on RHEL5.

Answer 1

Thank you.
That solved part of a problem. Now what if I want to satisfy a condition?
Considering the same above table, say I want to "value of Col_C when value of Col_A='D' - value of Col_C when value of Col_B='C'"?
abby007
I am trying to query the v$archived_log view. And currently 'm running the below 2 queries to find out the updated archives on the DR site and then manually subtracting it:
PhyStdby: SQL > select thread#, max(sequence#) "Last Standby Seq Received"
from v$archived_log val, v$database vdb
where val.resetlogs_change# = vdb.resetlogs_change#
group by thread# order by 1;
PhyStdby: SQL > select thread#, max(sequence#) "Last Standby Seq Applied"
from v$archived_log val, v$database vdb
where val.resetlogs_change# = vdb.resetlogs_change#
and applied='YES'
group by thread# order by 1;
I want to combine the above 2 queries so that I get a response like:
Thread#
Last Standby Seq Received
Last Standby Seq Applied
Total Lag
1
33778
33770
8
2
70244
70242
2
3
46972
46971
1