Another group by having problem I think ...

Question

I have a table defined like so ...
create table mytable (
subcode number,
name varchar2(10)
I suspect that I have records in this table that look like so ...
SUBCODE NAME
123 Jim
123 Mary
... this is bad.
I ran a query like this ...
select subcode, name, count(subcode) from mytable group by subcode, name having count(subcode) > 1
... and got back zero results.
Does this mean I DO NOT have duplicates?
Thanks

Answer 1

You do have duplicates but your statement doesn't show that since you are grouping by SUBCODE and NAME. Since your have the same SUBCODE but a different NAME for the duplicate SUBCODE you get only 1 result with your group by statement. Here are two examples:
select subcode, name, count(subcode)
from mytable
group by subcode, name
   SUBCODE COUNT(SUBCODE)
       123              2
select subcode, name, count(subcode)
from mytable
group by subcode, name
   SUBCODE NAME       COUNT(SUBCODE)
       123 JIM                     1
       123 MARY                    1This statement will give you what you are looking for:
select subcode, name
from mytable
where subcode = (select subcode
                    from mytable
                    group by subcode
                    having count(subcode) > 1);