In the first half of 2021, the real questions and answer analysis of software designers in the afternoon (1)

[Description] In order to reduce operating costs, reduce staff and increase efficiency, and provide a good parking experience, a parking lot operator wants to develop an unattended parking system. The main functions of the system are: 1. Information maintenance
. Set 管理人员the charging rules for parking spaces (total number, vacant parking spaces, etc.) . 2. Member registration. Provide mobile phone number, license plate number and other information to register, submit recharge information (level, payment account bound and authorized payment system for recharge or payment) Different levels and recharge amounts enjoy different parking discount points. 3. License plate recognition. When entering the parking lot, if there is (the number of vacant parking spaces is 1), it will automatically recognize the license plate number and then control the barrier. When the owner drives out of the parking lot, the license plate number will be recognized. After the billing is successful, the barrier gate control will be requested. 4. Billing. Update the departure time of the vehicle, and calculate the parking fee according to the calculation. If the owner is , prompt the parking fee: if the stored balance is enough for this parking fee, the fee will be automatically deducted. If the stored value balance is insufficient, the authorized payment account will be automatically used to request the payment system to pay , to get the payment status. If non-members park temporarily, the parking fee will be prompted, and the owner can call the self-service payment by scanning the payment code in the fee information to obtain the payment status. 5. Barrier gate control. According to sending release instructions to and receiving barrier gate execution status. If the execution status of the barrier gate is normal release, for the entering vehicle, the license plate number and its entry time information will be stored , and the number of vacant parking spaces will be modified; for the leaving vehicles , the number of vacant parking spaces will be modified. When there is a problem with the reset system of the gate (such as a power outage or a fault such as lifting the bar), and the execution status returned by it cannot be received within the specified time and the normal release, the system will send an abnormal alarm message to the management personnel. Afterwards, the management staff arranged for troubleshooting to ensure that vehicles entered and exited the parking lot in an orderly manner.基础信息
车主
车辆
计费规则会员更新余额支付系统
道闸控制请求道闸控制系统停车记录更新停车状态
Now adopt a structured method to analyze and design the unattended parking system, and obtain the context data flow diagram shown in Figure 1-1 and the 0-layer data flow diagram shown in Figure 1-2.

[Question 1] (5 points)
Using the words in the description, give the names of the entities E1-E5 in Figure 1-1.

E1:车辆；E2:车主；E3:支付系统；E4:管理人员；E5:道闸控制系统
【Question 2】(3 points)
Use the words in the instructions to give 数据存储the names of D1-D3 in Figure 1-2.

D1:停车记录表；D2:会员信息表；D3:基础信息表
【Question 3】(4 points)
According to the description and terms in the figure, supplement the missing data flow and its start and end points in Figure 1-2.

[Question 4] (3 points)
According to the instructions, use structured language to describe the processing logic of "barrier gate control".

"Barrier control" process

IF(道闸执行状态正常)
    IF(车辆入场) THEN 
        将车牌号及其入场时间信息存入停车记录，修改空余车位数
    ELSEIF(车辆出场) THEN 
        更新停车状态，修改空余车位数
    ENDIF 
    ELSESIF(未在规定的时间内接收到其返回的执行状态正常放行) THEN 
        向管理人员发送异常告警信息
ENDIF