Fictional teaching data. Keep source files unchanged.
6 order input rows -> 4 distinct order IDs -> 2 accepted orders + 2 exception IDs. A02 repeats exactly and counts once.
Accepted amount CNY 37.00; excluded amounts are not zero and must not enter the accepted subtotal.
A03 has 8.00/9.00 conflict and ambiguous 03/11/2026. Do not choose a locale or newer file without an explicit rule. A04 customer 009 is unmapped.