Analytics function is not allowed in Group By - sql

Question

I have a following query:
SELECT t.date,
t.transactionId,
t.channelGrouping,
tp.itemRevenue,
t.transactionItemQuantity,
t.company,
t.campaign,
ifnull(replace((regexp_extract(tp.productCategory, r"(^[a-zA-Z0-9_.&;+ -]+)")),"&", "&"), "N/A") as productCategory,
ifnull(sum(a.adCost),0) as adCost
FROM `kpi.TransactionsByChannel` t left join kpi.TransactionProducts tp
on tp.transactionId = t.transactionId
left join kpi.Ads a
on a.company = t.company and a.date = t.date and a.campaign = t.campaign group by 1,2,3,4,5,6,7,8
which returns me result:
However, as you can see, adCost is not correct and duplicated. I need to get ratio of it based on itemRevenue or just write first row and other rows should be 0.
I tried following query:
SELECT t.date,
t.transactionId,
t.channelGrouping,
tp.itemRevenue,
t.transactionItemQuantity,
t.company,
t.campaign,
ifnull(replace((regexp_extract(tp.productCategory, r"(^[a-zA-Z0-9_.&;+ -]+)")),"&", "&"), "N/A") as productCategory,
round(adCost*(itemRevenue/SUM(itemRevenue) over (partition by tp.company, tp.productCategory, tp.date)),2) as adCost_adjusted,
FROM kpi.TransactionsByChannel t left join kpi.TransactionProducts tp
on tp.transactionId = t.transactionId
left join kpi.Ads a
on a.company = t.company and a.date = t.date and a.campaign = t.campaign group by 1,2,3,4,5,6,7,8,9
but I am getting an error of:
Column 9 contains an analytic function, which is not allowed in GROUP BY at [13:99]
Any helps would be really appreciated!

Answer 1

Try something like this approach:
with ttr as
(
select
t.transactionId,
sum(tp.itemRevenue) as TotalItemRevenue
from
`kpi.TransactionsByChannel` t
inner join
kpi.TransactionProducts tp
on
tp.transactionId = t.transactionId
group by
t.transactionId
)
SELECT
t.date,
t.transactionId,
t.channelGrouping,
tp.itemRevenue,
t.transactionItemQuantity,
t.company,
t.campaign,
ifnull(replace((regexp_extract(tp.productCategory, r"(^[a-zA-Z0-9_.&;+ -]+)")),"&", "&"), "N/A") as productCategory,
ifnull(a.adCost,0) * tp.itemRevenue / ttr.TotalItemRevenue as adCost_adjusted
FROM
`kpi.TransactionsByChannel` t
inner join
ttr
on
t.transactionId = ttr.transactionId
inner join
kpi.TransactionProducts tp
on
tp.transactionId = t.transactionId
left join
kpi.Ads a
on
a.company = t.company
and a.date = t.date
and a.campaign = t.campaign