Getting Latest 3 orders by Supplier ID - sql

Question

I have the following SQL Server code to get information from a combination of 4 tables.
I would like to modify it to only retrieve the latest 3 orders (pmpOrderDate) by supplier (pmpSupplierOrganizationID).
SELECT
PO.pmpPurchaseOrderID, PO.pmpOrderDate, PO.pmpSupplierOrganizationID, O.cmoName
FROM
PurchaseOrders PO
INNER JOIN
PurchaseOrderLines POL ON PO.pmpPurchaseOrderID = POL.pmlPurchaseOrderID
INNER JOIN
Organizations O ON PO.pmpSupplierOrganizationID = O.cmoOrganizationID
INNER JOIN
Parts P ON POL.pmlPartID = P.impPartID
WHERE
P.impPartClassID LIKE 'PUMP%'
Can you please help?
EDIT:
I wasn't fully clear on my actual requirements. To clarify further, what I need in the end is to display the latest 3 unique Purchase Orders by Supplier ID based on at least one of the PartClassID for the PartID in the PurchaseOrderLines to have criteria of beginning with string 'PUMP'

Answer 1

Use a ROW_NUMBER to partition by pmpSupplierOrganizationID and order by pmpOrderDate.
with cteTopOrders AS (
SELECT PO.pmpPurchaseOrderID, PO.pmpOrderDate, PO.pmpSupplierOrganizationID, O.cmoName,
ROW_NUMBER() OVER(PARTITION BY pmpSupplierOrganizationID ORDER BY pmpOrderDate DESC) AS RowNum
FROM PurchaseOrders PO
Inner Join PurchaseOrderLines POL ON PO.pmpPurchaseOrderID = POL.pmlPurchaseOrderID
Inner Join Organizations O On PO.pmpSupplierOrganizationID = O.cmoOrganizationID
Inner Join Parts P ON POL.pmlPartID = P.impPartID
WHERE P.impPartClassID Like 'PUMP%'
)
SELECT pmpPurchaseOrderID, pmpOrderDate, pmpSupplierOrganizationID, cmoName
FROM cteTopOrders
WHERE RowNum <= 3;

Answer 2

I'm a fan of lateral joins for this . . . cross apply:
select p.*, O.cmoName
from Organizations O cross apply
(select top (3) PO.pmpPurchaseOrderID, PO.pmpOrderDate, PO.pmpSupplierOrganizationID
from PurchaseOrders PO join
PurchaseOrderLines POL
on PO.pmpPurchaseOrderID = POL.pmlPurchaseOrderID join
Parts P
on POL.pmlPartID = P.impPartID
where PO.pmpSupplierOrganizationID = O.cmoOrganizationID and
P.impPartClassID Like 'PUMP%'
order by PO.pmpOrderDate desc
) p

Answer 3

You need a nested row_number to get the three rows per supplier and another OLAP-function on top of it:
with OrderRowNum as
(
SELECT PO.pmpPurchaseOrderID, PO.pmpOrderDate, PO.pmpSupplierOrganizationID, O.cmoName, P.impPartClassID,
row_number()
over (partition by PO.pmpSupplierOrganizationID
order by pmpOrderDate desc) as rn
FROM PurchaseOrders PO
Inner Join PurchaseOrderLines POL ON PO.pmpPurchaseOrderID = POL.pmlPurchaseOrderID
Inner Join Organizations O On PO.pmpSupplierOrganizationID = O.cmoOrganizationID
Inner Join Parts P ON POL.pmlPartID = P.impPartID
)
, CheckPUMP as
(
select *,
-- check if at least one of the three rows contains PUMP
max(case when impPartClassID Like 'PUMP%' then 1 else 0 end)
over (partition by PO.pmpSupplierOrganizationID) as PUMPflag
from OrderRowNum
where rn <= 3 -- get the last three rows per supplier
)
select *
from CheckPUMP
where flag = 1