How to pull the whole row which has the latest date in SQL? - sql

Question

I’m trying to select the pair of product – distribution center attached with the most recent order (based on order date). For one order I can have multiple products, but the whole order will be shipped from one specific distribution center.
How do I select the specific product-distribution center attached with the latest order?
My structure is basically like this:
data.orderdetail table has ordernum, orderdate, distributioncenter
I tried to pull like this, but it doesn’t give me the desired result. I’m using sql server 2008:
SELECT DISTINCT y.OrderNum, y.Product, y.DistributionCenter
, CAST(y.OrderDate AS DATE) AS Orderdate
FROM (SELECT OrderNum, MAX(CAST(Orderdate AS date)) AS orderdate
FROM data.OrderDetail
GROUP BY OrderNum) AS x
INNER JOIN data.OrderDetail AS y
ON y.OrderNum = x.OrderNum

Answer 1

It looks as if you need one more clause in your join Condition
You've got
ON y.OrderNum = x.OrderNum
Which will return all the orders that match the Order number in the subquery
But you'll need
ON y.OrderNum = x.OrderNum
AND y.OrderDate = x.orderdate
Which will return all the orders that match the Order number in the subquery and the maximum date for that order number
SELECT DISTINCT
y.OrderNum,
y.Product,
y.DistributionCenter,
CAST(y.OrderDate AS DATE) AS Orderdate
FROM (
SELECT
OrderNum,
MAX(CAST(Orderdate AS date)) AS orderdate
FROM data.OrderDetail
GROUP BY OrderNum
) AS x
INNER JOIN
data.OrderDetail AS y
ON y.OrderNum = x.OrderNum
AND y.OrderDate = x.orderdate

Answer 2

I believe what you are looking for is row_number. This will partition your result set by OrderNum then rank the sets by the OrderDate. You can then filter off the extra rows in another where clause.
select result.*,
CAST(result.OrderDate as date) as Orderdate,
from (
select y.*,
row_number() over (
partition by y.OrderNum order by CAST(y.OrderDate as date) desc
) rank_
from (
select OrderNum,
MAX(CAST(Orderdate as date)) as orderdate
from data.OrderDetail
group by OrderNum
) as x
inner join data.OrderDetail as y on y.OrderNum = x.OrderNum
) result
where result.rank_ = 1;

Answer 3

select * from
(
SELECT OrderNum, Product, DistributionCenter, OrderDate
, ROW_NUMBER() over (partition by OrderNum order by OrderDate desc) as rownum
FROM OrderDetail
) as xxx
where xxx.rownum = 1
ROW_NUMBER (Transact-SQL)

Answer 4

Try this.
; WITH CTE1
AS (
SELECT
od.OrderNum
, od.Product
, od.DistributionCenter
, CAST(od.OrderDate AS DATE) AS OrderDate
, RowNumber = ROW_NUMBER() OVER (PARTITION BY od.Product, od.DistributionCenter ORDER BY CAST(od.OrderDate AS DATE) DESC)
FROM data.OrderDetail od
)
SELECT
OrderNum
, Product
, DistributionCenter
, OrderDate
FROM CTE1
WHERE RowNumber = 1