Oracle ORA-00979 - "not a GROUP BY expression"

Can anybody please help me with this particular query? I'm having ORA-00979 when trying to run this:

select   t0.title, count (1) as count0, (select   count (1)
      from contract c1, se se1
      where c1.c_id = se1.c_id
      and se1.svc_id = 3
      and se1.deleted = 0
      and c1.deleted = 0
      and c1.c_date between to_date ('07.10.2000', 'dd.mm.yyyy') 
                        and to_date ('22.11.2010', 'dd.mm.yyyy')
      and c1.company = 0
      and c1.tdata.tariff = c0.tdata.tariff
    ) as count1
  from contract c0, se se0, tariff t0
  where c0.c_id = se0.c_id
  and se0.svc_id = 3
  and se0.deleted = 0
  and c0.deleted = 0
  and c0.c_date between to_date ('21.11.开发者_C百科2000', 'dd.mm.yyyy') 
                and to_date ('06.01.2011', 'dd.mm.yyyy')
  and c0.company = 0
  and t0.tariff_id = c0.tdata.tariff
  group by t0.title

The problem is your subquery with the select count(1) part. Just because it's got a count in it doesn't actually make it an aggregate. It's still a subquery that will be applied to every row and as you can see it uses the value c0.tdata.tariff which is not part of the group.

Looks like that scalar subquery is causing the problem -- it is neither a group function, nor is it in the GROUP BY list.

Probably you could workaround it with something like:

select   t0.title, count (1) as count0, SUM(select   count (1) ...) AS count1
 ...

Considering this seems to be two instances of the same query just over different dates (I might be wrong here...it's been a long day), you could probably just simplify it and rewrite like this:

select
  t0.title, 
  count (case when c0.c_date between to_date ('21.11.2000', 'dd.mm.yyyy') 
                and to_date ('06.01.2011', 'dd.mm.yyyy') then 1 end) as count0,
  count (case when c0.c_date between to_date ('07.10.2000', 'dd.mm.yyyy') 
                and to_date ('22.11.2011', 'dd.mm.yyyy') then 1 end) as count1
from 
  contract c0, 
  se se0, 
  tariff t0
where 
  c0.c_id = se0.c_id
  and se0.svc_id = 3
  and se0.deleted = 0
  and c0.deleted = 0
  and (c0.c_date between to_date ('21.11.2000', 'dd.mm.yyyy') 
                and to_date ('06.01.2011', 'dd.mm.yyyy')
    or c0.c_date between to_date ('07.10.2000', 'dd.mm.yyyy') 
                        and to_date ('22.11.2010', 'dd.mm.yyyy'))
  and c0.company = 0
  and t0.tariff_id = c0.tdata.tariff
group by t0.title

Your group by needs to include all of the non-aggregate columns from your select list. In this case, the group by is missing the count1 returned by your subquery.