April 25, 2013 at 12:40 am
Hi
I am a complete novice and would like some help. I have a table (see attached image) that i need to query and return the average cost for the latest 3 supply dates. Some items may have one or 100 records. Let me know if you need any further information. Any help would be great.
Cheers
Cory
April 25, 2013 at 4:44 am
Any time you need to write a query, I usually take the approach of breaking it down into steps. For example, you need to see the average cost for each item, start there:
SELECT AVG(x.Cost)
FROM dbo.MyTable AS x
GROUP BY x.ItemID;
That will give you the averages. Then, you've specified a filter, the last three days. So you need to add a WHERE clause to limit the data that is being grouped. Further, you need to do a little date math to subtract three days from the current date. Since this sure sounds like homework, rather than just giving you the final answer, I'll link to the information you need.
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning
April 25, 2013 at 5:24 am
Thanks Very much for the help Grant you have defiantly pointed me in the right direction. I was almost there but it was one were i was heading down the wrong path. As you can see below I was looking for the top 3 dates not not 3 days from [today]. But I didn't explain it to well 🙂 Again Thanks for the information
SELECT x.ItemID, AVG(Cost)as Cost
FROM dbo.Inventory_tb AS x
where RecordID in
(
select TOP 3 RecordID
from Inventory_tb as b
where b.ItemID = x.ItemID
)
GROUP BY x.ItemID;
April 25, 2013 at 5:53 am
I would just add an ORDER BY clause to that TOP query. You can't guarantee the order of the data without it.
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning
April 25, 2013 at 6:43 am
Just did found a few odd results. Again thanks.
April 25, 2013 at 7:56 am
something like this:-
SELECT SUM(UnitPrice)
FROM
(SELECT TOP 3 UnitPrice FROM Sales.SalesOrderDetail
ORDER BY ModifiedDate DESC )t
April 26, 2013 at 12:29 am
April 26, 2013 at 3:44 am
elfishae15 (4/26/2013)
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"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning
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