在mongodb中创建一个计算字段

Question

我有两个集合，一个是员工，另一个是薪水。我想在员工收款电话月薪中创建一个计算字段。如何从 Salary 集合中访问 SALARY 并除以 12？

以下是我在 MongoDB 中包含的一些信息：

db.Salary.insertMany([

  {
    "POSITION": "1",
    "BRANCH_SIZE": "HQ",
    "SALARY": "150000"
  },
  {
    "POSITION": "2",
    "BRANCH_SIZE": "HQ",
    "SALARY": "100000"
  },
  {
    "POSITION": "3",
    "BRANCH_SIZE": "HQ",
    "SALARY": "70000"
  },
  {
    "POSITION": "4",
    "BRANCH_SIZE": "HQ",
    "SALARY": "30000"
  },
  {
    "POSITION": "5",
    "BRANCH_SIZE": "HQ",
    "SALARY": "56000"
  }
])

db.Employee.insertMany([

  {
    "EMPLOYEE_NO": "1000",
    "LNAME": "Wyatt",
    "FNAME": " Stefan"
    "CITY": "MANKATO",
    "STATE": "MN",
    "ZIP": "56001",
    "STATUS": "1",
    "POSITION": "1"
  },
  {
    "EMPLOYEE_NO": "1029",
    "LNAME": "Martin",
    "FNAME": "Edward",
    "STATUS": "1",
    "START_DATE": "02-MAY-95",
    "END_DATE": "",
    "BRANCH_NO": "103",
    "BRANCH_SIZE": "MD",
    "POSITION": "3"
  },
  {
    "EMPLOYEE_NO": "1089",
    "LNAME": "Stewart",
    "FNAME": "Macy",
    "CITY": "SAINT PAUL",
    "BRANCH_NO": "101",
    "BRANCH_SIZE": "BG",
    "POSITION": "4"
  }
])

我想为每个员工制定月薪。我怎样才能做到这一点？ 提前致谢。 任何帮助将不胜感激。

Answer 1

您可以使用$lookup 和$divide 运算符从工资集合中获取工资，并将其中一个字段除以12。

示例：

db.employee.aggregate([{
    $lookup: {
      from: 'salary',
      localField: 'POSITION',
      foreignField: 'POSITION',
      as: 'salary',
    },
  },
  {
    {
      $project: {
        dividedSalary: {
          $divide: ["$salary.SALARY", 12]
        }
      }
    }
  }
])