SQL GROUP BY on a sub query - sql

I have a query that will return results from 2 tables into 1 using a UNION ALL, which all works as I need it to. However I need to run a GROUP BY and an ORDER BY on the returned dataset however I am getting many errors and I'm not sure how to solve it.
Here is my Query:
SELECT ProductID, Quantity
FROM BasketItems
UNION ALL
SELECT ProductID, Quantity
FROM OrderItems
This will return a results set such as this:
ProductID Quantity
15 2
20 2
15 1
8 5
5 1
I then want to run a GROUP BY on the ProductID field and then finally an ORDER BY DESC on the Quantity field. So in the final output, this particular results set will finally result in this:
ProductID
8
15
20
5
I can then run queries on this result set as I usually do
EDIT:
As stated above, but maybe not implied enough is that I will need to run queries on the returned results, which isn't working as you cannot run a query on a set of results that have an ORDER BY clause (so far as I gathered from the error list)
If you want more information on the problem, here it is:
From this results set, I want to get the products from the product table that they relate to
SELECT * FROM Products WHERE ID IN (
SELECT ProductID
FROM
(
SELECT ProductID, Quantity
FROM BasketItems
UNION ALL
SELECT ProductID, Quantity
FROM OrderItems
) v
GROUP BY ProductID
ORDER BY SUM(Quantity) DESC
)
However, I get this error: The ORDER BY clause is invalid in views, inline functions, derived tables, subqueries, and common table expressions, unless TOP, OFFSET or FOR XML is also specified.
The output of products need to be in the order that they are returned in the sub query (By quantity)

SELECT Products.*
FROM Products
INNER JOIN
(
SELECT ProductID, Sum(Quantity) as QuantitySum
from
(
SELECT ProductID, Quantity
FROM BasketItems
UNION ALL
SELECT ProductID, Quantity
FROM OrderItems
) v
GROUP BY ProductID
) ProductTotals
ON Products.ID = ProductTotals.ProductID
ORDER BY QuantitySum DESC

will this work?
SELECT ProductID
from
(
SELECT ProductID, Quantity
FROM BasketItems
UNION ALL
SELECT ProductID, Quantity
FROM OrderItems
) temp
GROUP BY temp.ProductID
ORDER BY SUM(temp.Quantity) desc

Here's a cte version (no live test so please excuse blunders)
EDIT
;WITH myInitialdata_cte(ProductID,Quantity)
AS
(
SELECT ProductID, Quantity FROM BasketItems
UNION ALL
SELECT ProductID, Quantity FROM OrderItems
)
SELECT b.ID
FROM
myInitialdata_cte a
INNER JOIN Products b ON
a.ProductID = b.ID
GROUP BY ProductID
ORDER BY SUM(a.Quantity) DESC

Related

Get the date for each duplicated row in SQL Server

I've made a query to get how many products are sold more than one time and it worked.
Now I want to show the transaction date for each of these duplicated sales, but when I insert the date on the select it brings me a lot less rows: something is going wrong. The query without the date returns 9855 rows and with the date just 36 rows.
Here is the query I'm doing:
SELECT TransactionDate,
ProductName,
QtyOfSales = COUNT(*)
FROM product_sales
WHERE ProductID = 1 -- Product Sold ID
AND ProductName IS NOT NULL
GROUP BY ProductName,
TransactionDate
HAVING COUNT(*) > 1
Perhaps a subquery? Can you help in that regard?
You can use the corresponding COUNT window function, that will find the amount of transactions by partitioning on the "ProductName" as required:
WITH cte AS(
SELECT TransactionDate,
ProductName,
COUNT(*) OVER(PARTITION BY ProductName) AS QtyOfSales
FROM product_sales
WHERE ProductID = 1 -- Product Sold ID
AND ProductName IS NOT NULL
)
SELECT DISTINCT TransactionDate,
ProductName
FROM cte
WHERE QtyOfSales > 1

Retrieve top selling products

I would like to receive top 5 selling products in quantity in an order from NorthWind database.
The database has a bunch of tables like Order, OrderDetails, Customers, etc. I was suggested to use Orders Details table below:
Now, I tried the following:
WITH cte AS (
SELECT
OrderID,
Quantity,
ProductID,
ROW_NUMBER() OVER(PARTITION BY OrderID ORDER BY OrderID) as row_num
FROM [Order Details]
)
SELECT *
FROM cte
WHERE row_num IN (SELECT row_num FROM cte WHERE row_num <=10)
ORDER BY OrderID;
Thought this retrieves 10 rows now for each order, they are not ordered based on sold quantities and top sold products are not retrieved properly as for some orders the top sold was beyond the first top 10 rows based on row number I got with ROW_NUMBER() function in SQL.
Edit: For example, if I have 10 orders each with 20 products, then I want top 5 each each product, so the result table should have 50 rows total.
After your edits:
WITH cte AS (
SELECT
OrderID,
Quantity,
ProductID,
ROW_NUMBER() OVER(PARTITION BY OrderID ORDER BY Quantity DESC) as row_num
FROM [Order Details]
)
SELECT *
FROM cte
WHERE row_num <= 5
ORDER BY OrderID;
You should do a
SELECT DISTINCT productid FROM OrderDetails ORDER BY quantity GROUP BY productId LIMIT 5
At least this is the mysql syntax.

SQL Select Group By Min() - but select other

I want to select the ID of the Table Products with the lowest Price Grouped By Product.
ID Product Price
1 123 10
2 123 11
3 234 20
4 234 21
Which by logic would look like this:
SELECT
ID,
Min(Price)
FROM
Products
GROUP BY
Product
But I don't want to select the Price itself, just the ID.
Resulting in
1
3
EDIT: The DBMSes used are Firebird and Filemaker
You didn't specify your DBMS, so this is ANSI standard SQL:
select id
from (
select id,
row_number() over (partition by product order by price) as rn
from orders
) t
where rn = 1
order by id;
If your DBMS doesn't support window functions, you can do that with joining against a derived table:
select o.id
from orders o
join (
select product,
min(price) as min_price
from orders
group by product
) t on t.product = o.product and t.min_price = o.price;
Note that this will return a slightly different result then the first solution: if the minimum price for a product occurs more then once, all those IDs will be returned. The first solution will only return one of them. If you don't want that, you need to group again in the outer query:
select min(o.id)
from orders o
join (
select product,
min(price) as min_price
from orders
group by product
) t on t.product = o.product and t.min_price = o.price
group by o.product;
SELECT ID
FROM Products as A
where price = ( select Min(Price)
from Products as B
where B.Product = A.Product )
GROUP BY id
This will show the ID, which in this case is 3.

How to select the appropriate record/records from a group of records when using either MAX or MIN aggregate functions

How to select the appropriate record/records from a group of records when using either MAX or MIN aggregate functions so that the record/records match the value returned by the aggregate function?
I need to use the NorthWind.products database table ( http://www.zentut.com/wp-content/uploads/downloads/2013/06/Northwind-Sample-Database-Diagram.pdf ) in order to find the most expensive product in each category. So far I have tried two variants:
SELECT CategoryID, ProductID, ProductName, MAX(UnitPrice) MostExpensive
FROM [NORTHWND].[dbo].[Products] as A
GROUP BY CategoryID;
This code produces the error "Column 'NORTHWND.dbo.Products.ProductID' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause." I have perfectly understood the reason. It's OK.
The second variant was:
SELECT CategoryID, ProductID, ProductName
FROM [NORTHWND].[dbo].[Products] as A
WHERE UnitPrice = (
SELECT MAX(UnitPrice) FROM [NORTHWND].[dbo].[Products] AS B GROUP BY CategoryID HAVING A.CategoryID = B.CategoryID
)
This one works fine, the records returned are the right ones, but I would like to have 4 columns in the first SELECT, the fourth should be the maximum price in each category. Can I change the SQL query to achieve that or should I tried a third variant?
For SQL Server >= 2005:
SELECT *
FROM (
SELECT CategoryID,
ProductID,
ProductName,
UnitPrice,
RowNum = ROW_NUMBER() OVER (PARTITION BY CategoryID ORDER BY UnitPrice DESC)
FROM dbo.Products
) t
WHERE t.RowNum = 1
For SQL Server < 2005:
SELECT DISTINCT
p.CategoryID,
p.ProductID,
p.ProductName,
p.UnitPrice
FROM dbo.Products p
JOIN (
SELECT CategoryID, UnitPrice = MAX(UnitPrice)
FROM dbo.Products
GROUP BY CategoryID
) t ON t.UnitPrice = p.UnitPrice AND t.CategoryID = p.CategoryID

SQL Query: SELECT MAX SUM quantity

How do i combine a SUM and MAX in a single query?
Lets say i have a orderrule:
ProductID \ Quantity
I Could say:
Select ProductID,SUM(Quantity) AS Sold
FROM Orderrule
GROUP BY ProductID
ORDER BY SUM(Quantity) Desc
However that would return all sales, and not just the most sold product (with quantity).
Try this
SELECT TOP(1)
*
FROM
(
Select
ProductID,
MAX(Quantity) As MaxQuantity,
SUM(Quantity) AS Sold
FROM Orderrule
GROUP BY ProductID
)AS X
ORDER BY Sold DESC
So there are two ways to do it - first to have a limit on the number of results, something likes:
select * from (your_select) where rownum = 1
the other one is to pick the one with the the highest value, which will require a subselect, something like:
having sum(quantity) =
(select max(sum_quan) from (select sum(Quantity) from orderrule group by Product_id))
SELECT TOP 1 ProductID, Sold FROM
(
SELECT ProductID, SUM(Quantity) AS Sold
FROM Orderrule
GROUP BY ProductID
) totals
ORDER BY Sold DESC