Datatable dt=new Datatable();

DataSet ds=new DataSet();           

SqlCommand cmd= new SqlCommand(SQL语句, SqlConnection对象);
using (SqlDataAdapter dataAdapter = new SqlDataAdapter())
{
         dataAdapter.SelectCommand = cmd;
         dataAdapter.Fill(ds, "dt");
         if (ds.Tables["dt"] != null)
         {
               dt = ds.Tables["dt"].Copy();
          }
          dataAdapter.Dispose();
}
//取值
string ID="";
string Type="";
for(int i=0;i<dt.Rows.Count;i++){
    ID += dt.Rows[i]["ID"].ToString();
    Type += dt.Rows[i]["Type"].ToString();
}