× The internal search function is temporarily non-functional. The current search engine is no longer viable and we are researching alternatives.
As a stop gap measure, we are using Google's custom search engine service.
If you know of an easy to use, open source, search engine ... please contact support@midrange.com.


  1.  Home
  2. MIDRANGE-L
  3. September 2001

RE: Elementary SQL question

>> From: Matthias Oertli
>>
>> Given a customer master file (one record per customer) and a
>transaction
>> file (one record per transaction, one customer can have many
>> transactions), how would it be possible to find the average number of
>> transactions per customer with one single SQL statement?

>You need count(*) of the transaction file divided by count(*) of the
>customer master.  I can't see any way of doing that in one statement.

I guess I don't understand what is being asked.  If I do a count of
transactions divided by a count of masters, doesn't that do funny things if
say, all the transactions belong to one master?

Here's my submission:

select avg(count) from
  (select count(*) as count from transactionfile
     group by customernumber) as average

  --buck

As an Amazon Associate we earn from qualifying purchases.

This thread ...
Follow-Ups:
Follow On AppleNews
Return to Archive home page | Return to MIDRANGE.COM home page

This mailing list archive is Copyright 1997-2025 by midrange.com and David Gibbs as a compilation work. Use of the archive is restricted to research of a business or technical nature. Any other uses are prohibited. Full details are available on our policy page. If you have questions about this, please contact [javascript protected email address].

Operating expenses for this site are earned using the Amazon Associate program and Google Adsense.