Append without duplicates

[Theresa]

Hi, I am very frustrated.
I have two queries:
SelectAdditional
SelectBasic
I want to append the data in SelectAdditional without appending any records that already exist. First I am trying to select only the non-duplicate records. I have a query that reads as follows:
Field Student BID BasicPointer
Table SelectAdditional SelectAdditional SelectBasic
Criteria Is Null

The tables are joined on BasicPointer and BID

I feel this should work, but it dosen't! I returns a blank table. If I remove the criteria the query returns the common records not the non-common records.
This is 2010 working in compatable mode wit 2003.

What am I doing wrong? Does anyone agree this should work?
Thanks
Theresa

 

[MStef]

Send a short example of your MDB, (Access2002-2003 or Access2000),
and tell what you want to do.

 

[pr2-eugin]

So much information but not really understandable or helpful. Please provide some code/sample DB to help us help you. Also tell us what you are trying to achieve.