构建空Datatable

  DT = new DataTable();
            DataRow DR = DT.NewRow();
            //构建列（名称，数据类型）
            DT.Columns.Add("代码", Type.GetType("System.String"));
            DT.Columns.Add("进价", Type.GetType("System.String"));
            DT.Columns.Add("售价", Type.GetType("System.String"));
            DT.Columns.Add("原因", Type.GetType("System.String"));
            DT.Columns.Add("原进价", Type.GetType("System.String"));
            DT.Columns.Add("原售价", Type.GetType("System.String"));
           //构建第一条数据
            DR["代码"] = TxtCode.Text.Trim();
            DR["进价"] = TxtJinPrice.Text.Trim();
            DR["售价"] = TxtShouPrice.Text.Trim();
            DR["原因"] = TxtYuanYin.Text.Trim();
            DR["原进价"] = OldPring;
            DR["原售价"] = OldPrice;
            DT.Rows.Add(DR);
            a = 1;

DataTable  tblDatas = newDataTable("Datas");
DataColumn dc = null;
  
//赋值给dc，是便于对每一个datacolumn的操作
dc =tblDatas.Columns.Add("ID",Type.GetType("System.Int32"));
dc.AutoIncrement= true;//自动增加
dc.AutoIncrementSeed = 1;//起始值1
dc.AutoIncrementStep = 1;//步长为1
dc.AllowDBNull = false;//
  
dc = tblDatas.Columns.Add("Product",Type.GetType("System.String"));
dc = tblDatas.Columns.Add("Version",Type.GetType("System.String"));
dc = tblDatas.Columns.Add("Description",Type.GetType("System.String"));
  //添加两条数据
  //* datatable 行数据可以叠加
DataRow newRow;
newRow = tblDatas.NewRow();
newRow["Product"] = "大话西游";
newRow["Version"] = "2.0";
newRow["Description"] = "我很喜欢";
tblDatas.Rows.Add(newRow);
  
newRow = tblDatas.NewRow();
newRow["Product"] = "梦幻西游";
newRow["Version"] = "3.0";
newRow["Description"] = "比大话更幼稚";
tblDatas.Rows.Add(newRow);

DataTable tblDatas = newDataTable("Datas");
tblDatas.Columns.Add("ID", Type.GetType("System.Int32"));
tblDatas.Columns[0].AutoIncrement = true;
tblDatas.Columns[0].AutoIncrementSeed = 1;
tblDatas.Columns[0].AutoIncrementStep = 1;
  
tblDatas.Columns.Add("Product",Type.GetType("System.String"));
tblDatas.Columns.Add("Version",Type.GetType("System.String"));
tblDatas.Columns.Add("Description",Type.GetType("System.String"));
  //直接添加三条数据
tblDatas.Rows.Add(newobject[]{null,"a","b","c"});
tblDatas.Rows.Add(newobject[] { null, "a", "b", "c" });
tblDatas.Rows.Add(new object[] { null, "a", "b", "c" });
tblDatas.Rows.Add(new object[] { null, "a", "b", "c" });
tblDatas.Rows.Add(new object[] { null, "a", "b", "c" });