John500
asked on
Help with query against AdventureWorks database - Average Sale Price
Need a hand with this query:
Return the average Sale Price by Product Category
Thanks!
Return the average Sale Price by Product Category
Thanks!
ASKER
Kevin,
Yep, that helps. Appreicate that.
Out of curiosity, do you feel you have the latest version of the database:
http://msftdbprodsamples.codeplex.com/releases/view/4004
Thanks
Yep, that helps. Appreicate that.
Out of curiosity, do you feel you have the latest version of the database:
http://msftdbprodsamples.codeplex.com/releases/view/4004
Thanks
My code above was pseudo code and not meant to be the actual structure from the codeplex. As stated above, I realized after answering a couple that it would be better to teach you the concept than write code for you. Take the information from above and try your hand at the code against the AdventureWorks tables yourself.
If you have difficulty, then post back here the query you have constructed and what issues you are having with it.
If you have difficulty, then post back here the query you have constructed and what issues you are having with it.
ASKER CERTIFIED SOLUTION
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Your sales table has:
SalesPrice
ProductId
Your product table has:
ProductId
CategoryId
Your category table has:
CategoryId
CategoryName
What you will need to do is figure out whether you want ALL product categories regardless of having parts assigned and/or having sales. If you want to have all categories you would use a LEFT JOIN, if only those with sales (INNER) JOIN.
For the product and sales data we will use a JOIN for both. Let's start with that:
select p.categoryid, avg(s.salesprice) as avgsalesprice
product p
inner join sales s on p.productid = s.productid
group by p.categoryid
What this gives you is your average sales by category id.
Now we apply our category table to it:
select c.categoryname
, coalesce(sls.avgsalesprice
from category c
left join (
select p.categoryid, avg(s.salesprice) as avgsalesprice
product p
inner join sales s on p.productid = s.productid
group by p.categoryid
) sls on c.categoryId = sls.categoryId
;
What we have done here is to put our previous query as a derived table with alias "sls" and then joined on the categoryid. Now we can display a category name and its average sales price or 0 using coalesce to filter nulls or no sales.
Hope that helps.
Kevin