[Ur] Possible to have products in SQL aggregates?

[Daniel Patterson]

That was giving me compile errors, and I thought it wasn't supported
in that way. If that works, then I'll just figure out the compile
errors (they must have been due to something else). Sorry for the
trouble!

On Fri, May 31, 2013 at 9:16 PM, Adam Chlipala <adamc at csail.mit.edu> wrote:
> I'm having trouble seeing the issue here.  Why doesn't the following code do
> what you're asking, in a completely idiomatic SQL-y way?
>
> table a : { AId : int }
> table aBJoin : { RefA : int, RefB : int }
> table b : { BId : int, RefA : int, Quantity: float }
> table c : {Token : int, RefB : int, Quantity: float }
>
> val q : sql_query [] [] _ _ =
>     (SELECT a.AId, SUM(c.Quantity * b.Quantity)
>      FROM c JOIN b ON c.RefB = b.BId
>        JOIN aBJoin ON aBJoin.RefB = b.BId
>        JOIN a ON a.AId = aBJoin.RefA
>      GROUP BY a.AId)
>
>
> On 05/31/2013 06:39 PM, Daniel Patterson wrote:
>>
>> I have a table structure like:
>>
>> A: aId
>>
>> ABJoin: refA, refB
>>
>> B: bId, refA, quantity: float
>>
>> C: token, refB, quantity: float
>>
>> The goal is, for a given token, to give a list of all the relevant As,
>> by joining C with B on refB = bId and then joining B and A through the
>> ABJoin table. I _want_ to see SUM(C.quantity * B.quantity) - ie the
>> total number of the specific A that is relevant for the referenced
>> token, but I'm not able to write that product. (I could if I were just
>> using SQL)
>>
>> Is there a way to do this? I'd prefer not to bring everything into
>> code and then re-implement the join and aggregate...
>>
>
>
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