Re: Need help building this query

From: rihad(at)stream(dot)az
To: "Oliver d'Azevedo Christina" <oliveiros(dot)cristina(at)asperger-talents(dot)com>
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: Need help building this query
Date: 2012-06-22 04:40:08
Message-ID: f12d27729c6897cdf2759658005931f1.squirrel@mail.azuni.net
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> For matching triples (foo, bar, baz) the date in table B shouldnt always
> be
> after any date in table A, as table B contains complete operations?
>
Operations in Table B can usually be obtained a day after, when Table A
gets the updates. Table B contains the physical date of operation. The
date in Table A are today's dates because this is how the reports feeding
them is generated. Those are only dates, no time parts. Date_of_op is
actually a settlement date (banking term) and TableA is more recent than
TableB for reasons irrelevant to the problem (and which suck).

>
> Best,
> Oliver
>
> ----- Original Message -----
> From: "Rihad" <rihad(at)stream(dot)az>
> To: <pgsql-sql(at)postgresql(dot)org>
> Sent: Thursday, June 21, 2012 6:48 PM
> Subject: [SQL] Need help building this query
>
>
>> Hi, folks. I currently need to join two tables that lack primary keys,
>> and
>> columns used to distinguish each record can be duplicated. I need to
>> build
>> statistics over the data in those tables. Consider this:
>>
>>
>> TableA:
>> row 1: foo: 123, bar: 456, baz: 789, amount: 10.99, date_of_op: date
>> row 2: foo: 123, bar: 456, baz: 789, amount: 10.99, date_of_op: date
>> row 3: foo: 123, bar: 456, baz: 789, amount: 10.99, date_of_op: date
>>
>> TableB:
>> row 1: foo: 123, bar: 456, baz: 789, amount: 10.99, date_of_op: date
>>
>>
>> Columns foo + bar + baz are used to distinguish a performed "operation":
>> TableA.date_of_op isn't, because it can lag behind TableB.
>>
>> Not all different "operations" are in table B.
>> Table B is just there so we know which "operations" are complete, so to
>> speak (happening under external means and not under any of my control).
>>
>> Now, for each operation (foo+bar+baz) in table A, only *one* row should
>> be
>> matched in table B, because it only has one matching row there.
>> The other two in TableA should be considered unmatched.
>>
>> Now the query should be able to get count(*) and sum(amount) every day
>> for
>> that day, considering that matched and unmatched operations should be
>> counted separately. The report would look something like this:
>>
>> TableA.date_of_op TableB.date_of_op
>> 2012-06-21 [empty] [count(*) and sum(amount)
>> of all data in TableA for this day unmatched in TableB]
>> 2012-06-21 2012-06-20 [count(*) and sum(amount) of
>> all data in TableA matched in TableB for the 20-th]
>> 2012-06-21 2012-06-19 [count(*) and sum(amount) of
>> all data in TableA matched in TableB for the 19-th]
>>
>>
>> Can this awkward thing be done in pure SQL, or I'd be better off using
>> programming for this?
>>
>> Thanks, I hope I could explain this.
>>
>> --
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>>
>
>
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