Compute average for three periods of times - sql

Question

I have the following three queries which get the average price for a product for three specific period of times: all data, last 7 days and last 30 days.
SELECT AVG(Price) AS AggregatedPrice, COUNT(*) AS PCount
FROM dbo.Products
WHERE Id = #id
SELECT AVG(Price) AS AggregatedPrice, COUNT(*) AS PCount
FROM dbo.Products
WHERE Id = #id AND DATEDIFF(day, UpdatedDatetime, getdate()) < 7
SELECT AVG(Price) AS AggregatedPrice, COUNT(*) AS PCount
FROM dbo.Products
WHERE Id = #id AND DATEDIFF(day, UpdatedDatetime, getdate()) < 30
Those three queries give me the right data, but not in the form I want. Is there a way to combine those three queries into one. My final goal is to create a view with all this data on one row.
In addition, it appears to me that the average computed for the 7 days could be reused for the 30 days and all the list. Is there an optimization that I can do?

Answer 1

SELECT #Id
, t1.AggregatedPrice AggregatedPrice_ALL, t1.PCount PCount_ALL
, t2.AggregatedPrice AggregatedPrice_7, t2.PCount PCount_7
, t3.AggregatedPrice AggregatedPrice_30, t3.PCount PCount_30
FROM
(SELECT Id, AVG(Price) AS AggregatedPrice, COUNT(*) AS PCount
FROM dbo.Products
WHERE Id = #id) t1
JOIN
(SELECT Id, AVG(Price) AS AggregatedPrice, COUNT(*) AS PCount
FROM dbo.ApplicationPrice
WHERE Id = #id AND DATEDIFF(day, UpdatedDatetime, getdate()) < 7) t2
ON t1.Id = t2.id
JOIN
(SELECT Id, AVG(Price) AS AggregatedPrice, COUNT(*) AS PCount
FROM dbo.ApplicationPrice
WHERE Id = #id AND DATEDIFF(day, UpdatedDatetime, getdate()) < 30) t3
ON t1.Id = t3.id

Answer 2

Something like this. Make sure to test properly
SELECT
AVG(Price) AS AggregatedPrice
, COUNT(*) AS PCount
, AVG(CASE WHEN DATEDIFF(day, UpdatedDatetime, getdate()) < 7 THEN Price ELSE Null End) AS AggregatedPrice7Days
, SUM(CASE WHEN DATEDIFF(day, UpdatedDatetime, getdate()) < 7 THEN 1 ELSE 0 End) AS AggregatedPrice7Days
, AVG(CASE WHEN DATEDIFF(day, UpdatedDatetime, getdate()) < 30 THEN Price ELSE Null End) AS AggregatedPrice30Days
, SUM(CASE WHEN DATEDIFF(day, UpdatedDatetime, getdate()) < 30 THEN 1 ELSE 0 End) AS AggregatedPrice30Days
FROM
dbo.Products
WHERE
Id = #id

Answer 3

I don't have T-SQL handy to test the syntax, but it should be something like this:
SELECT t1.AggregatedPrice, t1.PCount, t2.AggregatedPrice, t2.PCount, t3.AggregatedPrice, t3.PCount
FROM
(SELECT AVG(Price) AS AggregatedPrice, COUNT(*) AS PCount FROM dbo.Products WHERE Id = #id) t1,
(SELECT AVG(Price) AS AggregatedPrice, COUNT(*) AS PCount FROM dbo.Products WHERE Id = #id AND DATEDIFF(day, UpdatedDatetime, getdate()) < 7) t2,
(SELECT AVG(Price) AS AggregatedPrice, COUNT(*) AS PCount FROM dbo.Products WHERE Id = #id AND DATEDIFF(day, UpdatedDatetime, getdate()) < 30) t3

Answer 4

Try this:
SELECT AVG(Price) AS AggregatedPrice,
COUNT(*) AS PCount,
AVG(CASE WHEN DATEDIFF(day, UpdatedDatetime, getdate()) < 7 THEN Price ELSE NULL END) AS AggregatedWeekPrice,
COUNT(CASE WHEN DATEDIFF(day, UpdatedDatetime, getdate()) < 7 THEN 1 ELSE NULL END) AS PWeekCount,
AVG(CASE WHEN DATEDIFF(day, UpdatedDatetime, getdate()) < 30 THEN Price ELSE NULL END) AS AggregatedMonthPrice,
COUNT(CASE WHEN DATEDIFF(day, UpdatedDatetime, getdate()) < 30 THEN 1 ELSE NULL END) AS PMonthCount,
FROM dbo.Products
WHERE Id = #id