for (int i = 0; i < GridView1.Rows.Count; i++)
      {
          CheckBox cb = (CheckBox)GridView1.Rows[i].Cells[0].FindControl("ck1");
          if (cb.Checked)
          {
              //这里写插入到tabel2代码
          }
      }

------解决方案--------------------
C# code
      for (int i = 0; i < GridView1.Rows.Count; i++)
      {
          CheckBox cb = GridView1.Rows[i].FindControl("CheckBox1") as CheckBox;
          if (cb.Checked)
          {
              插入table表;
          }
      }

------解决方案--------------------

      for (int i = 0; i < DataList1.Items.Count; i++)
     {
         CheckBox cb = DataList1.Items[i].FindControl("CheckBox1") as CheckBox;
         if (cb.Checked)
         {
             插入table表;
         }
     }