这是一个使用Python示例代码的解决方案，用于按净收入而不是订单日期来总结员工。

# 定义员工的收入数据
employee_data = [
    {"name": "John", "order_date": "2021-01-01", "revenue": 500},
    {"name": "John", "order_date": "2021-02-01", "revenue": 700},
    {"name": "John", "order_date": "2021-03-01", "revenue": 600},
    {"name": "Lisa", "order_date": "2021-01-01", "revenue": 800},
    {"name": "Lisa", "order_date": "2021-02-01", "revenue": 900},
    {"name": "Lisa", "order_date": "2021-03-01", "revenue": 1000},
]

# 创建一个字典来存储员工的净收入
employee_net_income = {}

# 遍历员工数据
for employee in employee_data:
    name = employee["name"]
    revenue = employee["revenue"]
    
    # 如果员工已存在于字典中，则将净收入累加到现有的净收入上
    if name in employee_net_income:
        employee_net_income[name] += revenue
    else:
        employee_net_income[name] = revenue

# 打印总结结果
for name, net_income in employee_net_income.items():
    print(f"{name}: {net_income}")

运行以上代码将输出：

John: 1800
Lisa: 2700

该代码使用一个字典(employee_net_income)来存储每个员工的净收入。在遍历员工数据时，如果员工已存在于字典中，则将净收入累加到现有的净收入上；否则，将该员工的净收入添加到字典中。最后，使用循环打印出每个员工的净收入总和。