Basically I am trying to combine certain fields from two tables into one using an append query.  The trick comes in that I want to only include records that have changed since the query was last run.  When I first run my query, I get the results expected to populate the desired table (Unit_Bid_test).

I must not be nesting my WHERE Clause correctly, because I can pass updates from my Unit_Pricing table just fine, but updates made to my Eligible_Bidders table are unseccessful.  Here is the base query:


I have added criteria to the WHERE clause in an attempt to limit the appending of the table to new records:


This seems to work for updates made to the Unit_Pricing table, but not updates made to the Eligible_Bidders table.

Any idea how to nest the WHERE statement to correct this issue?

Lack access to the DB right now, but I think my issue was using:


and not





 

What are the primary keys for each table?

My table structure is as follows:


The Eligible_Bidders table is created using a many to many relationship between a Projects table and a Contractors table.  The Projects_ID field is also found in the Unit_Pricing table to that Project Managers can add a unit cost to a given project.  

And I have confirmed that the changes work:


I am now working to incorporate a delete query which will check for Unit Prices and Contractors that have been removed from the Unit_Pricing and Eligible_Bidders tables as well:


My question now is what best practice should I be using to execute these queries in succession?  Can I combine them into a single query?  Should I run them via VBA to ensure that the delete is done prior to the append?