构建空Datatable

方法一

  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;

方法二

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);

方法三

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" });

 方法四（根据情况构建多条数据）

  DataTable DT = new DataTable();
            DataRow DR = DT.NewRow();
            for(int a = 0 ;a<dataGridViewX1.Columns.Count;a++)
            {
            DT.Columns.Add(dataGridViewX1.Columns[a].HeaderCell.Value.ToString(),Type.GetType("System.String"));
            }
            int RowCount = dataGridViewX1.Rows.Count;
            int CellCount = dataGridViewX1.Columns.Count;
            for (int a = 0; a < RowCount-1; a++)
            {//新实例化数据
                DR = DT.NewRow();
                
                for (int b = 0; b < CellCount; b++)
                {
                  // dataRow 构建行数据 构建一条添加一条
                   DR[b] = dataGridViewX1.Rows[a].Cells[b].Value.ToString();
                }
                DT.Rows.Add(DR);
                
            }