List Transactions that Meet Criteria - sql

Question

Realizing that another question I asked before may be too difficult, I'm changing my requirements.
I work for a credit card company. Our database has a customer table and a transaction table. Fields in the customer table are SSN and CustomerKey. Fields in the transaction table are CustomerKey, transaction date (Transdate), and transaction amount (TransAmt).
I need a query that can identify each ssn where the sum of any of their transaction amounts > 1000 within a two day period in 2012. If a ssn has transaction amounts > 1000 within a two day period, I need the query to return all the transactions for that ssn.
Here is an example of the raw data in the Transaction Table:
Trans#-----CustKey-----Date--------Amount
1-----------12345----01/01/12--------$600
2-----------12345----01/02/12--------$500
3-----------67890----01/03/12--------$10
4-----------98765----04/01/12--------$600
5-----------43210----04/02/12--------$600
6-----------43210----04/03/12--------$100
7-----------13579----04/02/12--------$600
8-----------24568----04/03/12--------$100
Here is an example of the raw data in the Customer Table:
CustKey-----SSN
12345------123456789
67890------123456789
98765------987654321
43210------987654321
13579------246801357
24568------246801357
Here are the results I need:
Trans#------SSN---------Date---------Amount
1--------123456789----01/01/12---------$600
2--------123456789----01/02/12---------$500
3--------123456789----01/03/12----------$10
4--------987654321----04/01/12---------$600
5--------987654321----04/02/12---------$600
6--------987654321----04/03/12---------$100
As you can see in my results included all transactions for SSN 123456789 and 987654321, and excluded SSN 246801357.

Answer 1

One way of doing this is to roll through each two day period within a year. Here is an SQL Fiddle example.
The idea is pretty simple:
1) Create a temp table to store all matching customers
create table CustomersToShow
(
SSN int
)
2) Loop trough a year and populate temp table with customers that match the amount criteria
declare #firstDayOfTheYear datetime = '1/1/2012';
declare #lastDayOfTheYear datetime = '12/31/2012';
declare #currentDate datetime = #firstDayOfTheYear;
declare #amountThreshold money = 1000;
while #currentDate <= #lastDayOfTheYear
begin
insert into CustomersToShow(SSN)
select b.SSN
from transactions a
join customers b
on a.CustKey = b.CustKey
where TransactionDate >= #currentDate
and TransactionDate <= DATEADD(day, 2, #currentDate)
group by b.SSN
having SUM(a.TransactionAmount) >= #amountThreshold
set #currentDate = DATEADD(day,2,#currentDate)
end
3) And then just select
select a.TransNumber, b.SSN, a.TransactionDate, a.TransactionAmount
from transactions a
join customers b
on a.CustKey = b.CustKey
join CustomersToShow c
on b.SSN = c.SSN
Note: This will be slow...

Answer 2

While you could probably come up with a hacky way to do this via standard SQL, this is a problem that IMO is more suited to being solved by code (i.e. not by set-based logic / SQL).
It would be easy to solve if you sort the transaction list by customerKey and date, then loop through the data. Ideally I would do this in code, but alternatively you could write a stored procedure and use a loop and a cursor.

Answer 3

This is easy and well-suited to set-based logic if you look at it right. You simply need to join to a table that has every date range you're interested in. Every T-SQL database (Oracle has it built-in) should have a utility table named integers - it's very useful surprisingly often:
CREATE TABLE integers ( n smallint, constraint PK_integers primary key clustered (n))
INSERT integers select top 1000 row_number() over (order by o.id) from sysobjects o cross join sysobjects
Your date table then looks like:
SELECT dateadd(day, n-1, '2012') AS dtFrom, dateadd(day, n+1, '2012') AS dtTo
from integers where n <= 366
You can then (abbreviating):
SELECT ssn, dtFrom
FROM yourTables t
JOIN ( SELECT dateadd(day, n-1, '2012') as dtFrom, dateadd(day, n+1, '2012') AS dtTo
from integers where n <= 366 ) d on t.date between d.dtFrom and d.dtTo
GROUP BY ssn, dtFrom
HAVING sum(amount) > 1000
You can select all your transactions:
WHERE ssn in ( SELECT distinct ssn from ( <above query> ) t )