Am I doing this right???

[dallr]

The "AS" keyword is optional in the FROM Clause when Alaising tables in Microsoft Access, hence I left it out.

 

[MSherfey]

Got it. Thanks!

Logically, could I change the 'min' to a 'count'? It looks like it would make a table with their IDs and the count of purchases in that time frame. I would then look for counts greater than 1.

I'm starting to get a small understanding of your query so I thought I'd try it a few different ways to make sure I got it.

Thanks again, this is very simple query is really helping me grasp what I think is a pretty advanced topic.

 

[MSherfey]

I thought I had a grasp of what was happening in the subquery, but I can't seem to get this to work. When I run the query, it doesn't return any errors but instead it just runs forever. I let it run for about 5 minutes before I closed it. Traditionally, the two separate queries and the third un-matched query would take about 30 seconds to complete.

Any ideas?

SELECT DISTINCT [Invoice Data].[EndUser OCN:], [Invoice Data].[Invoice Quarter:], (SELECT DISTINCT [P2].[Invoice Quarter:] 
     FROM [Invoice Data] AS P2 
     WHERE [P2].[EndUser OCN:]=[Invoice Data].[EndUser OCN:] AND [P2].[Invoice quarter:]="2009 Q2") AS 2009_Cust
FROM [Invoice Data]
WHERE ((([Invoice Data].[Invoice Quarter:])="2008 Q2"));

 

[MSAccessRookie]

It does not look like you have joined the table [Invoice Data] to the Table [P2] anywhere. This will result in what is referred to as a Cartesian Join, which requires comparisons between every row of the table [Invoice Data] to every other row of the table [Invoice Data]. You can imagine that the more rows that you have in the table [Invoice Data], the longer it will take. You will need to create a Join between them on a unique column to prevent this from happening.

 

[MSherfey]

You are right. Thank you.

I had to add the subquery to the LEFT JOIN section. Man, that took a bit of figuring out

All in all, this is working. Thank you to everyone who helped. (I clicked on the scales next to your names.)

SELECT DISTINCT [Invoice Data].[EndUser OCN:]
FROM [Invoice Data] LEFT JOIN (SELECT DISTINCT [Invoice Data].[EndUser OCN:] FROM [Invoice Data] WHERE ((([Invoice Data].[Invoice Quarter:])="2009 Q2") ))  AS P2 ON [Invoice Data].[EndUser OCN:] = P2.[EndUser OCN:]
WHERE ((([Invoice Data].[Invoice Quarter:])="2008 Q2") AND ((P2.[EndUser OCN:]) Is Null));

This thread started out with an accuracy question and you helped me answer that as well as streamline the process. Now I have one query and not three. Imagine that over 5 years of data and you saved me a TON of work!

Thanks again!