Create Subset of Table Based on Two Fields
Posted on 2008-09-29
Here are some easy points for someone smarter than myself, which probably includes most reading this question!
I have two tables (tblResults and tblRequested) that share 3 common fields: SampleID, AnalyteID, Requested. Although none of the shared fields is unique in either table, the combination of SampleID and AnalyteID IS unique. For example, there are many occurrences of SampleID=14 and many of AnalyteID=3, but there will only ever be one record where SampleID=14 AND AnalyteID=3.
Some of the records in tblRequested correspond (based on SampleID and AnalyteID) to records in tblResults. But some records do not. I would like to create a query that selects those records in tblRequested which are not found in tblResults, based on the values SampleID and AnalyteID.
Thanks in advance!