Session

By data set to data table
//Select data
private DataTable dtPruductForGridGrid()
{
string connStr = ConfigurationSettings.AppSettings["MyDbConn2"].ToString();
SqlConnection cn = new SqlConnection(connStr);
SqlDataAdapter cmd = new SqlDataAdapter("SELECT a.* from Tb_Product a ,cn);
DataSet dsProduct = new DataSet();
cmd.Fill(dsProduct, "Tb_Product");
DataTable dt = dsProduct.Tables["Tb_Product"];
Session["Tb_Product"] =dt;
return dt;
}

//Bind data on grid
private void PaintGrid()
{
DataTable dt = (DataTable)Session["Tb_Product"];
DataView dv = dt.DefaultView;
dv.Sort = "seq desc";
dgdshow.DataSource = dv;
dgdshow.DataBind();
}

Remark
If Session["tablename"] = Dataset
{
datatable dt = Dataset.table["tablename"]
}
else if Session["tablename"] = datatable
{
datatable dt = (datatable)Session["tablename"];
}
else if Session["tablename"] = string
{
string x = Session["tablename"].tostring();
}