Re: Window function SQL - can't quite figure it.

​You never asked a question...

I suppose your actual problem is that

group_key,

sum(amount) over (...)

GROUP BY​

​group_key

Is giving you an error.  This is expected.  You must write that fragment

group_key,

sum(sum(amount)) over (...)

GROUP BY group_key

The window sum is not an aggregate from the perspective of group by.  In the original you never aggregated "amount" nor was it part of the group by and thus an error.  turning "amount" into the aggregate "sum(amount)" is one valid solution.

David J.

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