SQL: How to find the MAX value/price of a particular item? - sql

Question

I am new to SQL and was wondering if anyone could guide me.
Here is my code and table output:
Code
Prices that are lower than 2.25 are appearing. I only want the 2.25 (highest) values.
I've tried removing the MAX in the select statement, removing the grouping,and replacing the WHERE statement with
WHERE Price = (
SELECT MAX(Price)
FROM tblPurchaseOrderLine
)
AND tblProduct.Description LIKE 'Alpine Small Pot'
buuut it gave no output.
SOLUTION:
SELECT tblPurchaseOrder.PONumber 'PO Number',
tblVendor.Name 'Vendor Name',
tblProduct.ProductID 'Product ID',
tblProduct.Description,
MAX(tblPurchaseOrderLine.Price)'Price'
FROM tblPurchaseOrder
INNER JOIN tblVendor
ON tblVendor.VendorID = tblPurchaseOrder.VendorID
INNER JOIN tblPurchaseOrderLine
ON tblPurchaseOrderLine.PONumber = tblPurchaseOrder.PONumber
INNER JOIN tblProduct
ON tblProduct.ProductID = tblPurchaseOrderLine.ProductID
WHERE Price = (SELECT MAX(Price)
FROM tblPurchaseOrderLine
WHERE tblProduct.ProductID = tblPurchaseOrderLine.ProductID)
AND tblProduct.Description LIKE 'Alpine Small Pot'
GROUP BY tblPurchaseOrder.PONumber,tblVendor.Name,tblProduct.ProductID,tblProduct.Description
Thank you! I got it working

Answer 1

What you want in your case is a correlated subquery:
from tblPurchaseOrderLine t1
WHERE Price = (
SELECT MAX(Price)
FROM tblPurchaseOrderLine t2
where t1.product_id = t2.product_id
)
AND tblProduct.Description LIKE 'Alpine Small Pot'
There is a better way to do this:
You can do this using TOP 1 with window function in order clause:
select top 1 with ties t.*
from your_table t
where tblProduct.Description LIKE 'Alpine Small Pot'
order by row_number() over (
partition by product_id
order by price desc
);