Help Creating Query For "Duplicate Transactions"

[straw]

Hello Access Experts,

I have been tasked with a task that seem beyond my access knowledge base. The requirement is for Access to Upload a spreadsheet with Clients PC_ID of all Transactions. The PC_ID is the unique ID of all clients across 2 tables "The Master TX & Account Holder Table". So when the spreadsheet is uploaded the "Verified Y/N" field in the "Master Tx Table" should be marked as "D" (Duplicate) and a comment should then be added the "Account Holder Details Table" stating that the transaction has been previously paid. The "paid YorN" field in the "Master TX Table" should also be Marked as "N" (No)

If the query works, I then have to ensure that it is available to the payment team at the click of a button.

I hope my question makes sense and I hope your advise will help me complete the task.

I look forward to your feedbacks.

Regards,

[June7]

Not understanding data structure. Why is there a 'duplicate transaction'? Why a Y/N paid field? Isn't there already a payment date recorded with the transaction that could be used to determine Y/N? What is nature of Account Holder table?

If you want to provide db for analysis, follow instructions at bottom of my post.