RE: sql comparison between records

[Pete Hall <pbhall@xxxxxxxxxx>]

At 10:14 07/25/2001, you wrote:
>I need to calculate the average duration between records for records that
>can be grouped by key.  The real world application is mean time between
>clicks in a web site session.  Regardless, it's kind of interesting in the
>abstract, IMHO.  I was a big fan of Joe Celko's column when it used to
>appear in a now defunct freebie trade magazine.  One of the recurring
>implicit themes of his column was the difference between the types of
>problems that were naturally suited to a procedural language and those that
>were better suited to SQL.

How about something like this?

   Select SessionID,
          Minute(Max(TimeStamp) - Min(TimeStamp))/(Count(TimeStamp)-1) As 
Duration,
          Count(TimeStamp) - 1 As Pages
   From WebLog
   Group By SessionID

Pete Hall
pbhall@execpc.com
http://www.execpc.com/~pbhall/

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