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?


Best,
Oliver

----- Original Message ----- From: "Rihad" <ri...@stream.az>
To: <pgsql-sql@postgresql.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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