Question

我想加入两个对象并将它们组合成一个并使用LINQ执行平均查询。以下是我的课程

public class emp
  {
     public int empID { get; set; }
     public string empName { get; set; }
  }
public class salaries
  {
     public int empID { get; set; }
     public string month { get; set; }
     public int salary { get; set; }
   }

public void repository()
        {
            lstemp = new List<emp> { 
            new emp{empID=1,empName="A"},
            new emp{empID=2,empName="B"},
            new emp{empID=3,empName="C"}
            };

            lstsalary = new List<salaries> { 
            new salaries{empID=1,month="jan",salary=1000},
            new salaries{empID=1,month="feb",salary=1500},
            new salaries{empID=1,month="mar",salary=2000},

              new salaries{empID=2,month="jan",salary=1500},
            new salaries{empID=2,month="feb",salary=2000},

              new salaries{empID=3,month="jan",salary=1500},
            new salaries{empID=3,month="feb",salary=2000},
            new salaries{empID=3,month="mar",salary=2000},
            new salaries{empID=3,month="apr",salary=2000},
            };
        }
        static void Main()
        {
            new calculator().repository();
            var result = from e in calculator.lstemp
                         join
                             s in calculator.lstsalary on e.empID equals s.empID 
                             group s by s.empID into grp
                         select new {

                             salary = (from g in grp where g.empID == grp.Key select g.salary).Average()
                         };            
        }

现在从上面的数据我想根据empID进行分组，然后我想从他们各自的薪水中取平均值。

结果应该是empName和平均工资雇员。

如何实现这一目标。谢谢。

Answer 1

您可以将这两个对象存储为匿名类型，以访问您也可以按属性，ID和名称分组的empName：

var result = from e in calculator.lstemp
     join s in calculator.lstsalary on e.empID equals s.empID 
     let empSal = new { emp = e, sal = s }
     group empSal by new { empSal.emp.empID, empSal.emp.empName } into g
     select new
     {
         empName = g.Key.empName,
         salary = g.Average(x => x.sal.salary)
     };

如何使用LINQ在C＃对象上使用Join，GroupBy和Average

1 个答案: