Get average number during period - database

Question

I have a database that stores data from the stock market.
There is a table with 3 columns: stockId, date, and volume
New data will be inserted into the table every trading day.
How can I get a result like 'Average volume for each stock over the last 10 trading days'?

Answer 1

SELECT AVG(volume) FROM mytable WHERE date >= (CURDATE() - INTERVAL 10 DAY)
EDIT:
Last 10 day groups, and their averages.
SELECT AVG(volume) FROM mytable GROUP BY date ORDER BY date DESC LIMIT 10

Answer 2

http://sqlfiddle.com/#!6/c8dbb/4
CREATE TABLE Stocks
([StockId] int, [Date] DateTime, [Volume] int)
;
INSERT INTO Stocks
([StockId], [Date], [Volume])
VALUES
(1, GetDate(), 1000),
(1, GetDate()+1, 2000),
(1, GetDate()+2, 4000),
(2, GetDate(), 1000),
(2, GetDate()+1, 1000),
(2, GetDate()+2, 500)
;
Select StockId, AVG(Volume) [AverageVolume]
FROM Stocks
WHERE [Date] >= DATEADD(dd, 0, DATEDIFF(dd, 0, GetDate())) - 10
Group by StockId
Order by StockId

Answer 3

SELECT SUM(volume)/10 FROM table_name
Where date Between Cast('7/18/13 12:01:01' As DateTime) And Cast('7/08/13 12:01:01' as DateTime)

Answer 4

I'm basing this off of Dodecapus answer and based off of comments you've given to other answers. I'm just including query in answer but check out sqlfiddle for working example with data.
http://sqlfiddle.com/#!6/91599/2
SELECT
StockId
,AVG(Volume) [AverageVolume]
FROM Stocks
WHERE [Date] IN
(
SELECT DISTINCT TOP 10 [Date] FROM Stocks ORDER BY [Date] DESC
)
GROUP BY StockId
ORDER BY StockId
This will only work if there is a record of at least one stock with volume per trading day.

Answer 5

Fun little query to write. Here it is:
SELECT AVG(x.Volume) FROM (SELECT Volume FROM StockTable WHERE Date BETWEEN
DATE_ADD(NOW(), INTERVAL -10 DAY) AND NOW())x
This is what I used to build a sample table to work off of in SQLFiddle:
CREATE TABLE StockTable (ID INT PRIMARY KEY AUTO_INCREMENT NOT NULL, Date DATETIME, Volume INT);
INSERT INTO StockTable (Date, Volume) VALUES (DATE_ADD(NOW(), INTERVAL 12 DAY), 1000), (DATE_ADD(NOW(), INTERVAL 1 DAY), 5000),
(DATE_ADD(NOW(), INTERVAL 0 DAY), 3000), (DATE_ADD(NOW(), INTERVAL -11 DAY), 6000), (DATE_ADD(NOW(), INTERVAL -5 DAY), 4000), (DATE_ADD(NOW(), INTERVAL 7 DAY), 9000);
Here is a link to the SQLFiddle of the query in action.
Idea behind the query: I create a derived table x which contains just the volumes within the past 10 days. Then I calculate the average of the volumes contained in that table. Voilà!
EDIT:
I realized specifically what you are looking for after reading through the other answers and comments. You are looking to get the average for each stock in the stock market over the last 10 days.
I built the sample table off of this:
CREATE TABLE StockTable (StockId INT NOT NULL, Date DATETIME, Volume INT);
INSERT INTO StockTable (StockId, Date, Volume) VALUES (1, DATE_ADD(NOW(), INTERVAL 6
DAY), 1000), (2, DATE_ADD(NOW(), INTERVAL 1 DAY), 5000),
(2, DATE_ADD(NOW(), INTERVAL 0 DAY), 3000), (3, DATE_ADD(NOW(), INTERVAL -8 DAY),
6000), (1, DATE_ADD(NOW(), INTERVAL -5 DAY), 4000),
(2, DATE_ADD(NOW(), INTERVAL 7 DAY), 9000);
And the query to get your results are:
SELECT StockId, AVG(Volume) FROM StockTable WHERE Date BETWEEN DATE_ADD(NOW(),
INTERVAL -10 DAY) AND NOW() GROUP BY StockId
Here is a link to the SQLFiddle of the query in action.