No don't do this, there's no DBMS under here so don't do joins or sub-queries unless it's the last resort! QODBC users XML to interface with the Intuit qbXML SDK, so QuickBooks actually does the deleting and takes care of the delete operation - not QODBC.
You can delete the whole invoice by doing:
delete from Invoice where TxnID='5BAB-1197758658'
or just delete one of the invoice lines by doing:
delete from InvoiceLine where TxnID='5BAB-1197758658' and InvoiceLineTxnLineID='5BAF-1197758658' |