public class Person{ public string FirstName{set;get;} public string LastName{set;get;} public Person(){} public Person(string firstName, string lastName) { FirstName = firstName; LastName = lastName; }}List<Person> personList=new List<Person>();personList.Add(new Person() { FirstName = "Mickey", LastName = "Mouse" });personList.Add(new Person() { FirstName = "Mickey", LastName = "Mouse" });personList.Add(new Person() { FirstName = "zhang", LastName = "san" });string columnName="FirstName";var dics=personList.GroupBy(x => GetPropertyValue(x, columnName)).ToDictionary(x=>x.Key,x=>x.Count());foreach(var dic in dics){ textBox1.AppendText(string.Format("{0},{1}/r/n",dic.Key,dic.Value));}

//根據子項目id得到flowjump實體類 flowJumps = this.FlowJumps; //按工序groupby flowjumps IEnumerable<IGrouping<int, FlowJump>> query = flowJumps.GroupBy(pet => pet.processID, pet => pet); foreach (IGrouping<int, FlowJump> info in query) { List<FlowJump> sl = info.ToList<FlowJump>();//分組后的集合 //也可循環得到分組后，集合中的對象，你可以用info.Key去控制 //foreach (FlowJump set in info) //{ //} } 

var groupInfo = orderinfo.Info.GroupBy(m => m.xx).ToList();    foreach (var item in groupInfo)    {     string infotemp = item.Key;    }