表中某列的所有值转成List泛型集合

Posted 2020-09-01

代码如下：

//表dt中含有字段名称列
List<string> fieldList = dt.AsEnumerable().Select(t => t.Field<string>("字段名称")).ToList<string>();
//还可以
List<string> fieldList2=(from d in dt.AsEnumerable() select d.Field<string>("字段名称")).ToList<string>();

其中dt.AsEnumerable()得到datarow的集合，对于DataRow有一个Field<T>("列名")的方法：dr.Field<string>("字段名称")，得到字符串类型的值。

扩展：Lambda表达式和Linq

    class Program
    {
        static void Main(string[] args)
        {
            LinqDataTable();
        }
        public static string[,] infoArr = new string[,] { { "1", "百度", "baidu", "201303" }, { "2", "迅雷", "xunlei", "201302" }, { "3", "谷歌", "guge", "201301" } };
        protected static void LinqDataTable()
        {
            DataRow row;
            ClientStruct cs = new ClientStruct();
            DataTable dtTable = new DataTable();
            dtTable.Columns.Add(cs.ID);
            dtTable.Columns.Add(cs.Name);
            dtTable.Columns.Add(cs.Company);
            dtTable.Columns.Add(cs.CreatedDate);
            for (int i = 0; i < 3; i++)
            {
                row = dtTable.NewRow();
                row[cs.ID] = infoArr[i, 0];
                row[cs.Name] = infoArr[i, 1];
                row[cs.Company] = infoArr[i, 2];
                row[cs.CreatedDate] = infoArr[i, 3];
                dtTable.Rows.Add(row);
            }

            //遍历DataTable，取出所有的ID
            //第一种：
            List<string> lstID = (from d in dtTable.AsEnumerable()
                                  select d.Field<string>(cs.ID)).ToList<string>();


            //第二种：
            List<string> allId = dtTable.AsEnumerable().Select(d => d.Field<string>("ID")).ToList();

            //遍历DataTable，将其中的数据对应到ClientStruct中
            //第一种：
            List<ClientStruct> list = (from x in dtTable.AsEnumerable()
                                       orderby x.Field<string>(cs.Company)
                                       select new ClientStruct
                                       {
                                           ID = x.Field<string>(cs.ID),
                                           Name = x.Field<string>(cs.Name),
                                           Company = x.Field<string>(cs.Company),
                                           CreatedDate = x.Field<string>(cs.CreatedDate)
                                       }).ToList<ClientStruct>();

            //第二种：
            List<ClientStruct> list2 = dtTable.AsEnumerable().OrderBy(o => o.Field<string>(cs.Company)).Select(x => new ClientStruct
            {
                ID = x.Field<string>(cs.ID),
                Name = x.Field<string>(cs.Name),
                Company = x.Field<string>(cs.Company),
                CreatedDate = x.Field<string>(cs.CreatedDate)
            }).ToList<ClientStruct>();

            //遍历DataTable，并将上面的List结果存储到Dictionary中：
            Dictionary<string, ClientStruct> dic = list.ToDictionary(p => p.Company);

            //p作为string键值来存储
        }
    }
    /*遍历DataTable*/
    class ClientStruct
    {
        public string ID = "ID";
        public string Name = "Name";
        public string Company = "Company";
        public string CreatedDate = "CreatedDate";
    }