ORACLE GROUP BY和CASE WHEN同时使用时遇到的一些问题
话不多说，上源码
select
sum(case when chg.ar_ap = 0 and chg.currency = 1 then chg.amount else 0 end) profit_cny_ar,
sum(case when chg.ar_ap = 1 and chg.currency = 1 then chg.amount else 0 end) profit_cny_ap,
sum(case when chg.ar_ap = 0 and chg.currency = 2 then chg.amount else 0 end) profit_usd_ar,
sum(case when chg.ar_ap = 1 and chg.currency = 2 then chg.amount else 0 end) profit_usd_ap,
sum(case when chg.ar_ap = 0 and chg.currency = 3 then chg.amount else 0 end) profit_eur_ar,
sum(case when chg.ar_ap = 1 and chg.currency = 3 then chg.amount else 0 end) profit_eur_ap,
(case when jh.is_master = 1 then jh.job_id when rel.job_id is null then jh.job_id else rel.job_id end) job_id,
jh.mbl_no mbl_no
from acc_charge chg
left join job_head jh
on chg.job_id = jh.job_id
LEFT JOIN acc_bill bill
on (chg.bill_id = bill.bill_id)
LEFT JOIN job_head_rel rel
on chg.job_id = rel.rel_job_id
where ((chg.ar_ap = 0 and
(chg.bill_id in (SELECT distinct tk.bill_id
FROM job_ticket_rel jtr, acc_bill tk
WHERE jtr.object_type = 14
AND jtr.object_id = tk.bill_id
and tk.corp_head_id = 8
and tk.status != 9) or
chg.confirm_id in
(SELECT distinct tk.confirm_id
FROM job_ticket_rel jtr, acc_confirm tk
WHERE jtr.object_type = 13
AND jtr.object_id = tk.confirm_id
and tk.open_ticket_type != 1))) or
(chg.ar_ap = 1 and
(chg.bill_id is null or exists
(select 1
from acc_bill bill
where bill.bill_id = chg.bill_id
and bill.corp_head_id = 8))))
and chg.charge_class_type != 4
and exists (select 1
from sys_staff_right_charge right_charge
where is_ar = 1
and is_select = 1
and right_charge.charge_type_id = chg.charge_type_id)
group by job_id, jh.mbl_no;
这是我开发时候写的sql，结果group by的时候，显示job_id出错，然后将代码改为下面形式：
select max(a.profit_cny_ar), max(a.profit_cny_ap),
max(a.profit_usd_ar), max(a.profit_usd_ap),
max(a.profit_eur_ar), max(a.profit_eur_ap),
a.job_id, a.mbl_no
from
(select
sum(case when chg.ar_ap = 0 and chg.currency = 1 then chg.amount else 0 end) profit_cny_ar,
sum(case when chg.ar_ap = 1 and chg.currency = 1 then chg.amount else 0 end) profit_cny_ap,
sum(case when chg.ar_ap = 0 and chg.currency = 2 then chg.amount else 0 end) profit_usd_ar,
sum(case when chg.ar_ap = 1 and chg.currency = 2 then chg.amount else 0 end) profit_usd_ap,
sum(case when chg.ar_ap = 0 and chg.currency = 3 then chg.amount else 0 end) profit_eur_ar,
sum(case when chg.ar_ap = 1 and chg.currency = 3 then chg.amount else 0 end) profit_eur_ap,
(case when jh.is_master = 1 then jh.job_id when rel.job_id is null then jh.job_id else rel.job_id end)job_id,
-- nvl(rel.job_id, jh.job_id) job_id,
jh.mbl_no mbl_no
from acc_charge chg
left join job_head jh
on chg.job_id = jh.job_id
LEFT JOIN acc_bill bill
on (chg.bill_id = bill.bill_id)
LEFT JOIN job_head_rel rel
on chg.job_id = rel.rel_job_id
where ((chg.ar_ap = 0 and
(chg.bill_id in (SELECT distinct tk.bill_id
FROM job_ticket_rel jtr, acc_bill tk
WHERE jtr.object_type = 14
AND jtr.object_id = tk.bill_id
and tk.corp_head_id = 8 -
and tk.status != 9) or
chg.confirm_id in
(SELECT distinct tk.confirm_id
FROM job_ticket_rel jtr, acc_confirm tk
WHERE jtr.object_type = 13
AND jtr.object_id = tk.confirm_id
and tk.open_ticket_type != 1))) or -
(chg.ar_ap = 1 and
(chg.bill_id is null or exists
(select 1
from acc_bill bill
where bill.bill_id = chg.bill_id
and bill.corp_head_id = 8))))
and chg.charge_class_type != 4
and exists (select 1
from sys_staff_right_charge right_charge
where is_ar = 1
and is_select = 1
and right_charge.charge_type_id = chg.charge_type_id)) a
group by a.job_id, a.mbl_no;
结果还是报ORA-00937,NOT A SINGLE-GROUP GROUP FUNCTION 错误；
百般尝试之后还是没有好的解决办法，最后改成下面形式才不报错：
select
sum(case when chg.ar_ap = 0 and chg.currency = 1 then chg.amount else 0 end) profit_cny_ar,
sum(case when chg.ar_ap = 1 and chg.currency = 1 then chg.amount else 0 end) profit_cny_ap,
sum(case when chg.ar_ap = 0 and chg.currency = 2 then chg.amount else 0 end) profit_usd_ar,
sum(case when chg.ar_ap = 1 and chg.currency = 2 then chg.amount else 0 end) profit_usd_ap,
sum(case when chg.ar_ap = 0 and chg.currency = 3 then chg.amount else 0 end) profit_eur_ar,
sum(case when chg.ar_ap = 1 and chg.currency = 3 then chg.amount else 0 end) profit_eur_ap,
(case when jh.is_master = 1 then jh.job_id when rel.job_id is null then jh.job_id else rel.job_id end) job_id,
jh.mbl_no mbl_no
from acc_charge chg
left join job_head jh
on chg.job_id = jh.job_id
LEFT JOIN acc_bill bill
on (chg.bill_id = bill.bill_id)
LEFT JOIN job_head_rel rel
on chg.job_id = rel.rel_job_id
where ((chg.ar_ap = 0 and
(chg.bill_id in (SELECT distinct tk.bill_id
FROM job_ticket_rel jtr, acc_bill tk
WHERE jtr.object_type = 14
AND jtr.object_id = tk.bill_id
and tk.corp_head_id = 8
and tk.status != 9) or
chg.confirm_id in
(SELECT distinct tk.confirm_id
FROM job_ticket_rel jtr, acc_confirm tk
WHERE jtr.object_type = 13
AND jtr.object_id = tk.confirm_id
and tk.open_ticket_type != 1))) or
(chg.ar_ap = 1 and
(chg.bill_id is null or exists
(select 1
from acc_bill bill
where bill.bill_id = chg.bill_id
and bill.corp_head_id = 8))))
and chg.charge_class_type != 4
and exists (select 1
from sys_staff_right_charge right_charge
where is_ar = 1
and is_select = 1
and right_charge.charge_type_id = chg.charge_type_id)
group by (case when jh.is_master = 1 then jh.job_id when rel.job_id is null then jh.job_id else rel.job_id end), jh.mbl_no;
将case语句当成一个字段，加在group by后面，解决此问题，但是感觉这种做法是饮鸩止渴，不清楚原理，慎用。
空了一定回来刨根问底，FLAG在此！