Sa**** schrieb:
> On May 12, 10:55 am, Urs Metzger <u...@[EMAIL PROTECTED]
> wrote:
>> Sa**** schrieb:
>>
>>> Hi all,
>>> I have a query as follows:
>>> Select building, floor from T1
>>> I would like to limit the output where the building, floor combination
>>> is present only once in the output.
>>> For example, if the output is
>>> blgdA, 2
>>> bldgA, 3
>>> bldgA, 3
>>> bldgB, 1
>>> bldgB, 2
>>> bldgB, 2
>>> I would like to filter it so that the output is only
>>> blgdA, 2
>>> bldgB, 1
>>> I'm not sure about how to do this.
>>> Can someone help out?
>>> Thanks,
>>> Sa****
>> Search the docs for GROUP BY and HAVING.
>>
>> htht,
>> Urs Metzger
>
> Thank you.
> So I modified the query thus:
> select bldg, count(Floor)
> from T
> group by bldg
> having count(Floor) =1
>
> However, when I try to include the floor number
> select lbcode_key, count(floor ), floor
> it fails: ORA-00979: not a GROUP BY expression
> I want to be able to see the floor number.
> Also there is another field "type" and I need to filter it by this
> field as well, to include the regexp '%Switch'.
>
> So my original query should have been:
> Select building, floor from T1 where type like '%Switch'
>
> However, the where clause is disallowed when using group by and the
> having clause doesn't like this either.
>
> How do I do this?
You need to group by (at least) all columns which you
don't aggregate. And you don't need "count(floor)" in
the select list - you already know it to be 1.
WHERE is perfectly legal, but only before the GROUP BY
clause.
select bldg, floor
from T
where type like '%Switch'
group by bldg, floor
having count(*) = 1
hth,
Urs Metzger
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