C# list集合对多个字段group by 、并新增字段

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'} }; // 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
//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;} }
//转载至：http://blog.csdn.net/q107770540/article/details/7629681