一个简化的机票销售系统需求描述如下:
售票员根据旅客需要的航班,首先查询有无该航班机票。若有,则负责录入旅客的基本信息,并将指定的机票标志设置为售出;售票部经理可随时查询每一个航班的售票情况,并在当日结算时能计算出日营业额。
请画出该系统的0层DFD图和1层DFD图(注:1层分解为查询和录入、统计和计算两个处理)。
提示:Alice求机场的一位旅客帮忙告诉她怎样才能搭乘去纽约的航班。这位旅客说朝左拐,随后找Alice要搭乘的航空公司(airline),并要给Alice画张地图。
Alice: Excuse me, (51)
Passenger: Yes
Alice: I have a ticket to New York. (52)
Passenger: I can’t help you here. You have to go to the ticket counter. Follow this passage to the end, (53) and go two hundred yards. You’ll see a sign that says, "Check in". (54) .
Alice: Go down this hall to the end. Then go left
Passenger: That’s right. Here, (55) . Sometimes it’s confusing.
Alice: Thank you.
Passenger: My pleasure.
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