方法一:

DataTable tblDatas = new DataTable("Datas");
DataColumn dc = null;
dc = tblDatas.Columns.Add("ID", Type.GetType("System.Int32"));
dc.AutoIncrement = true;//自动增加
dc.AutoIncrementSeed = 1;//起始为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"));

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);

方法二:

DataTable tblDatas = new DataTable("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"));

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" });
tblDatas.Rows.Add(new object[] { null, "a", "b", "c" });
tblDatas.Rows.Add(new object[] { null, "a", "b", "c" });

方法三：
DataTable table = new DataTable ();

//创建table的第一列
DataColumn priceColumn = new DataColumn();
//该列的数据类型
priceColumn.DataType = System.Type.GetType("System.Decimal");
//该列得名称
priceColumn.ColumnName = "price";
//该列得默认值
priceColumn.DefaultValue = 50;

// 创建table的第二列
DataColumn taxColumn = new DataColumn();
taxColumn.DataType = System.Type.GetType("System.Decimal");
//列名
taxColumn.ColumnName = "tax";
//设置该列得表达式，用于计算列中的值或创建聚合列
taxColumn.Expression = "price * 0.0862";
// Create third column.
DataColumn totalColumn = new DataColumn();
totalColumn.DataType = System.Type.GetType("System.Decimal");
totalColumn.ColumnName = "total";
//该列的表达式，值是得到的是第一列和第二列值得和
totalColumn.Expression = "price + tax";

// 将所有的列添加到table上
table.Columns.Add(priceColumn);
table.Columns.Add(taxColumn);
table.Columns.Add(totalColumn);

//创建一行
DataRow row = table.NewRow();
//将此行添加到table中
table.Rows.Add(row);

//将table放在试图中
DataView view = new DataView(table);
dg.DataSource = view;

dg.DataBind();