As @Jici said, your data structure is not set up correctly.

I’m not sure of the best way to set this up. (perhaps searching this forum for similar “tracking” apps would provide some insight).

However, it would seem to me that you need to track if a “transaction” is open (Yes/No field). And the Borrowers would need a field for Transactions (list). This way you can see the current Books a Borrower has out, and the history of books checked out and returned by showing the Borrower’ s list of Transactions constrained by Open=Yes or Open=No.

You’ll need to have Workflows that create a new Transaction, then add the Transaction (result of step 1) to the Borrowers list of Transactions when they check out a book. Then another Workflow to change the Open? field to “No”, and set the date returned when the Book is returned.

Perhaps the Book datatype also needs a field of Transactions (list) so you can look at all the Transactions by Book. This can be done in the same workflow that creates the Transaction.

IDK, other than setting up the data structure is critical, and you should spend a lot of time figuring that out first before building the app.

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