Return details of the latest bill linked to the user - sql

Question

I have two different sources of information and I am trying to marry them together to get information relating to a customer and their last bill. I have managed to get details of each customer and their max billing period end date but I am unsure as to how I can then get the details from the associated bill. I have the following query:
SELECT new_mprnnumber,
new_customernumber,
MAX(b.billingPeriodEndDate) as 'Billed up to date'
FROM [CRM].[crm4_MSCRM].[dbo].[AccountExtensionBase] as a
inner join Billing.dbo.bill as b
on a.new_mprnnumber = b.MPRN
where new_accountstage = 7
and new_accounttype = 2
group by new_mprnnumber,
new_customernumber
GO
The bill has fields like amount due etc but I only want to return details of those from the max dated bill, any help would be greatly appreciated

Answer 1

Use a CTE with row_number()
with CTE as
(
select a.new_mprnnumber,
a.new_customernumber,
b.*,
row_number()
over (partition by new_customernumber -- add additional partitions as you would group bys
order by billingPeriodEndDate desc) as r_ord
from AccountExtensionBase a
inner join bill b
on a.new_mprnnumber = b.MPRN
where new_accountstage = 7
and new_accounttype = 2
)
select *
from CTE
where r_ord = 1

Answer 2

Put your query into a CTE and then link back to table bill:
WITH CTE AS (
SELECT new_mprnnumber,
new_customernumber,
MAX(b.billingPeriodEndDate) as MaxBillDate
FROM [CRM].[crm4_MSCRM].[dbo].[AccountExtensionBase] as a
inner join Billing.dbo.bill as b
on a.new_mprnnumber = b.MPRN
where new_accountstage = 7
and new_accounttype = 2
group by new_mprnnumber,
new_customernumber
)
SELECT b.*
FROM CTE c
INNER JOIN Billing.dbo.bill b ON c.MaxBillDate = b.billingPeriodEndDate AND c.new_mprnnumber = b.MPRN