C#教程之C#集合中根据多个字段分组 group by linq表

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  • C#教程之C#集合中根据多个字段分组 group by linq表

  • 2019-10-18 21:06 来源:www.js333com
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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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