如何用linq合并重复项？求救！

Question

能用Lambda 表达式最好，谢谢了

Answer 1

namespace ConsoleApplication1
{
    /// <summary>
    /// 商品
    /// </summary>
    public class GoodsInfo
    {
        /// <summary>
        /// 编号
        /// </summary>
        public string GoodsNO { get; set; }
        /// <summary>
        /// 数量
        /// </summary>
        public decimal GoodsNum { get; set; }
    }    class Program
    {
        static void Main(string[] args)
        {
            List<GoodsInfo> list = new List<GoodsInfo>();
            list.Add(new GoodsInfo() { GoodsNO = "NO.01", GoodsNum = 3 });
            list.Add(new GoodsInfo() { GoodsNO = "NO.02", GoodsNum = 1 });
            list.Add(new GoodsInfo() { GoodsNO = "NO.01", GoodsNum = 2 });
            list.Add(new GoodsInfo() { GoodsNO = "NO.03", GoodsNum = 4 });
            list.Add(new GoodsInfo() { GoodsNO = "NO.02", GoodsNum = 2 });            var result = from p in list
                         group p by p.GoodsNO into g
                         select new
                         {
                             GoodsNO = g.Key,
                             GoodsNum = g.Sum(x => x.GoodsNum)
                         };            result.ToList().ForEach(x => Console.WriteLine(x.GoodsNO + " " + x.GoodsNum));
        }
    }
}

Answer 2

var temp = (from p in list
                        group p by p.GoodsNO).Select(p => new
                        {
                            goodNo = p.Key,
                            goodSum = p.Sum(q => q.GoodsNum)
                        });

Answer 3

或者 var temp = list.GroupBy(p => p.GoodsNO).Select(p => new
            {
                goodNo = p.Key,
                goodSum = p.Sum(q => q.GoodsNum)
            });

Answer 4

 var temp = list.GroupBy(p => p.GoodsNO)
                          .Select(g => new GoodsInfo
                                               {
                                                     GoodsNO = g.Key,
                                                     GoodsNum =g.Sum(q => q.GoodsNum)
                                               });