Reputation: 908
I think I'm missing a simple step here but I can't seem to figure it out. I've read the other threads and they talk about grouping but I can't seem to put it all together right.
I have a simple table that holds inventory transactions. In each row, there is a quantity and a price. I want to get the sum of the quantity and the sum of the each price * each quantity.
Here's my query. If I remove the grouping, I get 1 result that is multiplied by the number of rows in the table. If I add the grouping, I get the correct result multiple times. Am I missing something here? I just feel like running a query to get 20k results when they all contain the same data would be pointless.
SELECT (SUM(i.quantity) - IFNULL(SUM(s.quantity), 0)) AS quantity,
SUM(i.unitprice * i.quantity) AS totalprice
FROM 02_01_transactions t
LEFT JOIN 02_01_transactions i
ON i.type = 1
AND i.active = 1
LEFT JOIN 02_01_transactions s
ON s.type = 2
AND s.active =1
GROUP BY t.id
Upvotes: 1
Views: 3541
Reputation: 17925
Here's my guess at what you were trying to accomplish:
select
sum(quantity * case type when 1 then 1 when 2 then -1 end) as quantity,
sum(unitprice * quantity) as totalprice
from 02_01_transactions
where type in (1, 2) and active = 1
Upvotes: 1
Reputation: 1987
Not sure there is a need for the joins (you are not joining on any common value) or the type = 2 rows if you are just subtracting them out. Is there a reason the following does not work?
-- Total quantity, total price of all type 1, active transactions.
SELECT SUM(quantity) AS quantity,
SUM(unitprice * quantity) AS totalprice
FROM 02_01_transactions
WHERE type = 1
AND active = 1
Upvotes: 2