T-SQL Subquery Max(Date) and Joins
Solution 1
Try this:
Select *,
Price = (Select top 1 Price
From MyPrices
where PartID = mp.PartID
order by PriceDate desc
)
from MyParts mp
Solution 2
Here's another way to do it without subqueries. This method will often outperform others, so it's worth testing both methods to see which gives the best performance.
SELECT
PRT.PartID,
PRT.PartNumber,
PRT.Description,
PRC1.Price,
PRC1.PriceDate
FROM
MyParts PRT
LEFT OUTER JOIN MyPrices PRC1 ON
PRC1.PartID = PRT.PartID
LEFT OUTER JOIN MyPrices PRC2 ON
PRC2.PartID = PRC1.PartID AND
PRC2.PriceDate > PRC1.PriceDate
WHERE
PRC2.PartID IS NULL
This will give multiple results if you have two prices with the same EXACT PriceDate (Most other solutions will do the same). Also, I there is nothing to account for the last price date being in the future. You may want to consider a check for that regardless of which method you end up using.
Solution 3
SELECT
MyParts.*,MyPriceDate.Price,MyPriceDate.PriceDate
FROM MyParts
INNER JOIN (SELECT Partid, MAX(PriceDate) AS MaxPriceDate FROM MyPrice GROUP BY Partid) dt ON MyParts.Partid = dt.Partid
INNER JOIN MyPrice ON dt.Partid = MyPrice.Partid AND MyPrice.PriceDate=dt.MaxPriceDate
Solution 4
In SQL Server 2005 and later use ROW_NUMBER()
:
SELECT * FROM
( SELECT p.*,
ROW_NUMBER() OVER(PARTITION BY Partid ORDER BY PriceDate DESC) AS rn
FROM MyPrice AS p ) AS t
WHERE rn=1
Solution 5
Something like this
SELECT *
FROM MyParts
LEFT JOIN
(
SELECT MAX(PriceDate), PartID FROM MyPrice group by PartID
) myprice
ON MyParts.Partid = MyPrice.Partid
If you know your partid or can restrict it put it inside the join.
SELECT myprice.partid, myprice.partdate, myprice2.Price, *
FROM MyParts
LEFT JOIN
(
SELECT MAX(PriceDate), PartID FROM MyPrice group by PartID
) myprice
ON MyParts.Partid = MyPrice.Partid
Inner Join MyPrice myprice2
on myprice2.pricedate = myprice.pricedate
and myprice2.partid = myprice.partid
Vladislav Ross
Updated on January 23, 2021Comments
-
Vladislav Ross over 3 years
I'm trying to join multiple tables, but one of the tables has multiple records for a partid with different dates. I want to get the record with the most recent date.
Here are some example tables:
Table: MyParts Partid Partnumber Description 1 ABC-123 Pipe 2 ABC-124 Handle 3 ABC-125 Light Table: MyPrices Partid Price PriceDate 1 $1 1/1/2005 1 $2 1/1/2007 1 $3 1/1/2009 2 $2 1/1/2005 2 $4 1/1/2006 2 $5 1/1/2008 3 $10 1/1/2008 3 $12 1/1/2009
If I was just wanted to find the most recent price for a certain part I could do:
SELECT * FROM MyPrice WHERE PriceDate = (SELECT MAX(PriceDate) FROM MyPrice WHERE Partid = 1)
However I want to do a join first and get back the correct price for all parts not just one. This is what I have tried:
SELECT * FROM MyParts LEFT JOIN MyPrice ON MyParts.Partid = MyPrice.Partid WHERE MyPart.PriceDate = (SELECT MAX(PriceDate) FROM MyPrice)
The results are wrong as it takes the highest price date of the entire table.
SELECT * FROM MyParts LEFT JOIN MyPrice ON MyParts.Partid = MyPrice.Partid WHERE MyPart.PriceDate = (SELECT MAX(PriceDate) FROM MyPrice WHERE MyPrice.Partid = MyParts.Partid)
That errors out.
What can I do to get the results I want.