SQL Server 2005 Query remove duplicates via date - sql-server-2005

Question

I searched and searched and can't seem to figure out this issue:
We have three tables which have data I need to collect and show in a view.
SELECT
C.FirstName, C.LastName,
aspnet_Membership.LoweredEmail,
MAX(Bill.Code) AS BCodes,
MAX(Bill.BillDate)
FROM
dbo.Client C
INNER JOIN
dbo.Bill ON C.Id = Bill.BId
INNER JOIN
dbo.aspnet_Membership ON aspnet_Membership.UserId = C.UserGUID
WHERE
((Bill.Code='ASDF'
OR Bill.Code='XYZ'
OR Bill.Code='QWE'
OR Bill.Code='JKL')
AND C.LastName!='Unassigned')
GROUP BY
LastName, FirstName, LoweredEmail, Code, BDate
Client table has: FirstName LastName and UserGuid
Bill table has: BCode, BillDate
aspnet_Membership table has: E-mail, UserId
RESULTS:
FirstName LastName E-mail BCode BillDate
FName1 Lname1 fname#isp.com XYZ 2010-05-13 00:00:00.000
Fname2 Lname2 fname2#isp2.com XYZ 2010-06-05 00:00:00.000
Fname2 Lname2 fname2#isp2.com ASD 2008-09-17 12:01:45.407
As you can see Fname2 shows up twice, only difference is in the BCode and BillDate.
How can I make this go with the latest date so I get Fname2 record with Bcode of XYZ with date of 2010-06-05.
Any help would be appreciated, thank you in advance.

Answer 1

Seeing that you're using SQL Server 2005, I would probably use a CTE (Common Table Expression) to do this - something like:
;WITH MyData AS
(
SELECT
c.FirstName, c.LastName,
asp.LoweredEmail,
b.Code AS BCodes, b.BillDate,
ROW_NUMBER() OVER (PARTITION BY c.LastName,c.FirstName
ORDER BY BillDate DESC) AS 'RowNum'
FROM
dbo.Client c
INNER JOIN
dbo.Bill b ON C.Id = b.BId
INNER JOIN
dbo.aspnet_Membership asp ON asp.UserId = c.UserGUID
WHERE
b.Code IN ('ASDF', 'JKL', 'QWE', 'XYZ')
AND c.LastName != 'Unassigned'
)
SELECT
FirstName, LastName, LoweredEmail, BCodes, BillDate
FROM
MyData
WHERE
RowNum = 1
This CTE with the ROW_NUMBER() clause will:
"partition" your data by (FirstName,LastName) - each pair of those values gets a new sequential "row number"
order those values within each partition by descending BillDate
So the resulting set of data has each newest entry for any (FirstName,LastName) group with RowNum = 1 - and that's the data I'm selecting from that CTE.
Does that work for you??

Answer 2

Perform a second join (using a LEFT JOIN) to find a later row in Bill table, and then filter any results where that join succeeds:
SELECT
C.FirstName, C.LastName,
aspnet_Membership.LoweredEmail,
MAX(Bill.Code) AS BCodes,
MAX(Bill.BillDate)
FROM dbo.Client C
INNER JOIN dbo.Bill
ON C.Id=Bill.BId
INNER JOIN dbo.aspnet_Membership
ON aspnet_Membership.UserId=C.UserGUID
LEFT JOIN dbo.Bill b2
ON Bill.BId = b2.BId and
b2.Code in ('ASDF','XYZ','QWE','JKL') and
b2.BDate > Bill.BDate
WHERE
b2.BId is null and
((Bill.Code='ASDF'
OR Bill.Code='XYZ'
OR Bill.Code='QWE'
OR Bill.Code='JKL')
AND C.LastName!='Unassigned')
GROUP BY LastName, FirstName, LoweredEmail, Code, BDate