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 How to calculate average number of days taken
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Posting Yak Master

107 Posts

Posted - 01/16/2014 :  07:15:19  Show Profile  Reply with Quote
Hi guys,

I am trying to figure out how to calculate the overall average number of days taken to complete something.

The two fields are enquiry_date (date enquiry is recorded) and complete_date (date enquiry completed/closed).

Each enquiry has a enquiry_number

Sample data typically looks like:

Enquiry number - enquiry_time - complete date
1 - 01/01/2014 - 12/01/2014
2 - 01/01/2014 - 11/01/2014
3 - 01/01/2014 - 10/01/2014
4 - 01/01/2014 - 07/01/2014
5 - 01/01/2014 - 12/01/2014
6 - 01/01/2014 - 04/01/2014


What is the piece of SQL which looks at the average date difference for each enquiry and then sums it all up to give an overall average number of days it takes?

I am a bit stuck!

Very Important crosS Applying yaK Herder

52326 Posts

Posted - 01/16/2014 :  07:17:58  Show Profile  Reply with Quote

SELECT SUM(DATEDIFF(dd,enquiry_time,[complete date]))*1.0/NULLIF(COUNT([Enquiry number]),0) AS AverageEnquiryTime
FROM Table

SQL Server MVP
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Posting Yak Master

107 Posts

Posted - 01/16/2014 :  10:00:41  Show Profile  Reply with Quote
Thanks Visakh!
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