C#集合中根据多个字段分组 group by linq表达式

 

 

void Main()
{
     var  empList =new List<Employee>
     {
        new Employee {ID = 1, FName = "John", Age = 23, Sex = M},
        new Employee {ID = 2, FName = "Mary", Age = 25, Sex = F},
        new Employee {ID = 3, FName = "Amber", Age = 23, Sex = M},
        new Employee {ID = 4, FName = "Kathy", Age = 25, Sex = F},
        new Employee {ID = 5, FName = "Lena", Age = 27, Sex = F},
        new Employee {ID = 6, FName = "Bill", Age = 28, Sex = M},
        new Employee {ID = 7, FName = "Celina", Age = 27, Sex = F},
        new Employee {ID = 8, FName = "John", Age = 28, Sex = M}
     };
       
  //这里是根据Age,Sex进行分组
// query with lamda expression g.Key代表Age和Sex两字段,Count为新增字段 // 最终返回的集合QueryWithLamda包含字段:Age、Sex、Count var QueryWithLamda = empList.GroupBy(x => new { x.Age, x.Sex}) .Select(g=>new {g.Key, Count=g.Count()}); //query with standard expression<br> //返回结果同上 var query=from el in empList group el by new {el.Age,el.Sex} into g select new {g.Key, Count=g.Count()}; foreach (var employee in query /* Or QueryWithLamda */ ) Console.WriteLine(employee.Count); } public class Employee { public int ID {get;set;} public string FName {get;set;} public int Age {get;set;} public char Sex {get;set;} }
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