Why does the subquery throw errors in a group by query? - sql

Question

Ok, I will try a 2nd attempt because the first one was not that intelligent
My Query:
SELECT distinct kg.datum,
sum(case when leis.code = 'Oph3001' then leis.anzahl END) as leis3001,
sum(case when leis.code = 'Oph3003' then leis.anzahl END) as leis3003,
(select nvl((select to_date(KG2.KURZTEXT, 'dd.mm.yyyy')from kg_eintraege kg2 where kg2.kgtitel_nr = 1003350007 and kg.fall_nr = kg2.fall_nr and kg.patient_nr = kg2.patient_nr and kg.kg_id = kg2.kontext),'') from dual) as real_datum
FROM kg_eintraege kg
INNER JOIN aufenthalte a
ON kg.patient_nr = a.patient_nr
and kg.fall_nr = a.fall_nr
INNER JOIN MF_LEIS_DIAG_OP_MD leis
on leis.aufenthalte_nr = a.nr
group by kg.datum, kg.kg_id
order by /*real_datum*/ kg.datum desc
The following subquery is causing the problem:
(select nvl((select to_date(KG2.KURZTEXT, 'dd.mm.yyyy')from kg_eintraege kg2 where kg2.kgtitel_nr = 1003350007 and kg.fall_nr = kg2.fall_nr and kg.patient_nr = kg2.patient_nr and kg.kg_id = kg2.kontext),'') from dual)
Puting it into the group by expression throws the ORA-22818 error ("subquery not allowed here").
Not puting it throws the ORA-00979 error ("not a group by expression").
Can someone help me?

Answer 1

You could use an outer join instead; something like:
SELECT distinct kg.datum,
sum(case when leis.code = 'Oph3001' then leis.anzahl END) as leis3001,
sum(case when leis.code = 'Oph3003' then leis.anzahl END) as leis3003,
to_date(KG2.KURZTEXT, 'dd.mm.yyyy') as real_datum
FROM kg_eintraege kg
INNER JOIN aufenthalte a
ON kg.patient_nr = a.patient_nr
and kg.fall_nr = a.fall_nr
INNER JOIN MF_LEIS_DIAG_OP_MD leis
on leis.aufenthalte_nr = a.nr
LEFT OUTER JOIN kg_eintraege kg2
on kg2.kgtitel_nr = 1003350007
and kg.fall_nr = kg2.fall_nr
and kg.patient_nr = kg2.patient_nr
and kg.kg_id = kg2.kontext
group by kg.datum, kg.kg_id, to_date(KG2.KURZTEXT, 'dd.mm.yyyy')
order by /*real_datum*/ kg.datum desc

Answer 2

you can use a subquery
select datum,
sum(case when code = 'Oph3001' then anzahl END) as leis3001,
sum(case when code = 'Oph3003' then anzahl END) as leis3003,
real_datum
from (
SELECT distinct kg.datum,
leis.code,
leis.anzahl,
(select nvl((select to_date(KG2.KURZTEXT, 'dd.mm.yyyy')from kg_eintraege kg2 where kg2.kgtitel_nr = 1003350007 and kg.fall_nr = kg2.fall_nr and kg.patient_nr = kg2.patient_nr and kg.kg_id = kg2.kontext),'') from dual) as real_datum
FROM kg_eintraege kg
INNER JOIN aufenthalte a ON kg.patient_nr = a.patient_nr
and kg.fall_nr = a.fall_nr
INNER JOIN MF_LEIS_DIAG_OP_MD leis on leis.aufenthalte_nr = a.nr
)
group by datum, kg_id, real_datum
order by /*real_datum*/ kg.datum desc