List根據指定字段進行分組C#

  var sql = @"update [TABLE] WITH (ROWLOCK)
                                                                          SET 
                                                                         匹配方式 = '{0}'  
                                                                         where ID in({1})";
//lissqls 是你要分組的泛型集合

   List<UpdateSqlHelper>lissqls=new List<UpdateSqlHelper>();

   var GroupList = lissqls.GroupBy(x => x.MatchType).Select(x => new{ MatchType = x.Key, ItemIDLis = x.ToList() });

//存儲更新語句
   List<string> update_bill_sql = new List<string>(); foreach (var item in GroupList) { List<int> itemids = new List<int>(); foreach (var itemID in item.ItemIDLis) { itemids.Add(itemID.ItemID); }  var newsql = string.Format(sql, item.MatchType, string.Join(",", Array.ConvertAll<int, string>(itemids.ToArray(), delegate (int x) { return x.ToString(); }))); update_bill_sql.Add(newsql); }

 

  public class UpdateSqlHelper
    {
        public string MatchType { get; set; }
        public int ItemID { get; set; }
        public string Guid { get; set; }
    }