brucesilver
asked on
MS SQL : Get average time between dates
I need to write an MS SQL to return the average time in days or months between all dates in a list. For example, a have an array containing the dates 10/2/2001, 11/5/2001, 12/18/2001, 02/04/2003. What SQL statement would return the average time between all dates?
ASKER
Sorry nmcdermaid
I don't know what I was thinking by talking about an array. I have a Access DB with one date field per record, such as would exist in a log of phone contacts. I need an SQL to get an average numer of days between calls to a certain contact, each contact having a unique ID number. The dates that the calls were made would be consecutive.
I don't know what I was thinking by talking about an array. I have a Access DB with one date field per record, such as would exist in a log of phone contacts. I need an SQL to get an average numer of days between calls to a certain contact, each contact having a unique ID number. The dates that the calls were made would be consecutive.
Don't worry I'm still on the case....
N
N
Can you post the table name, and the date and contact field names? I'll give you the SQL you need.
ASKER
Table name: accounts
Date field: ActivDate
Customer ID: Customerid
Much appreciate the attention to this issue.
I increased the points by 50.
It would appear to be a simple thing to do with Datediff, but DateDiff would require two dates to calculate, and there is but one date field in the table. The whole thing could of course be done programmatically, but with considerably more code.
Date field: ActivDate
Customer ID: Customerid
Much appreciate the attention to this issue.
I increased the points by 50.
It would appear to be a simple thing to do with Datediff, but DateDiff would require two dates to calculate, and there is but one date field in the table. The whole thing could of course be done programmatically, but with considerably more code.
You use the DMax function to retreive the previous date in the same record.... like so:
SELECT
DMax("[ActivDate]","accoun ts","[Acti vDate] < #" & Format([ActivDate],"mm/dd/ yyyy") & "# AND Customerid= '" & [Customerid] & "'") AS PreviousDate,
accounts.CallerID,
DateDiff("d",DMax("[ActivD ate]","acc ounts","[A ctivDate] < #" & Format([ActivDate],"mm/dd/ yyyy") & "#"),[ActivDate]) AS CallInterval
FROM accounts;
This query retreives:
PreviousDate: not required... only there for illustration
CallerID
CallInterval
For each record. Note that this part of the expression: ~ Format([ActivDate],"mm/dd/ yyyy") ~ was required to convert the date format to US style..... it should not be required but it was!!... you may find that you don't need it, you can just use ActivDate
Once you have this query workingm save it as a query (Called say qryCallInterval)
Then run this query to get the average interval
SELECT CallerID, AVG(CallInterval)
FROM qryCallInterval
If you want to filter on dates, just include ActivDate in all queries and filter on it in a where clause.
SELECT
DMax("[ActivDate]","accoun
accounts.CallerID,
DateDiff("d",DMax("[ActivD
FROM accounts;
This query retreives:
PreviousDate: not required... only there for illustration
CallerID
CallInterval
For each record. Note that this part of the expression: ~ Format([ActivDate],"mm/dd/
Once you have this query workingm save it as a query (Called say qryCallInterval)
Then run this query to get the average interval
SELECT CallerID, AVG(CallInterval)
FROM qryCallInterval
If you want to filter on dates, just include ActivDate in all queries and filter on it in a where clause.
ASKER
This is tremendous. I had long ago given up on this. Thank you!!
ASKER CERTIFIED SOLUTION
membership
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:
No response from brucesilver from 12/11/2003 comment
Award points to nmcdermaid is recommend.
Please leave any comments here within the next seven days.
PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!
planocz
EE Cleanup Volunteer
I will leave a recommendation in the Cleanup topic area that this question is:
No response from brucesilver from 12/11/2003 comment
Award points to nmcdermaid is recommend.
Please leave any comments here within the next seven days.
PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!
planocz
EE Cleanup Volunteer
Do you want some code that will get the average out of an date array?
If you want to put them into a table, are all dates consecutive?
In that case the SQL would something like this:
SELECT AVG(DATEDIFF(day,tblDates.
FROM
tblDates,
(SELECT MAX(DateField) As PreviousDateField FROM tblDates WHERE DateField < tblDates.DateField) tblPreviousDate