Because the starting point is not checked for cyclic data and 'Frankfurt' must not be connected again, it is eliminated in the connect BY clause (Arrival 'Frankfurt').
因为没有检查循环数据的起始点，并且不能再次连接到“法兰克福市”，所以将从CONNECTBY子句中删除该中转(Arrival'Frankfurt ')。
Because the starting point is not checked for cyclic data and 'Frankfurt' must not be connected again, it is eliminated in the connect BY clause (Arrival 'Frankfurt').
因为没有检查循环数据的起始点，并且不能再次连接到“法兰克福市”，所以将从CONNECTBY子句中删除该中转(Arrival'Frankfurt ')。
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