title: c# error with dataset update
body: <p>I have list of type string with name temp1 in this list i have a group of words for each word im calculating N00,N01,N10,N11,MI at last it is throwing exception <strong>Update unable to find TableMapping['sample'] or DataTable 'sample'.</strong>.plz help</p>
  
  <pre><code>DataSet dsSelectAll = new DataSet();
      SqlCommand cmdSelectAll = new SqlCommand("select * from sample", con);
      SqlDataAdapter daSelectAll = new SqlDataAdapter(cmdSelectAll);
      SqlCommandBuilder scb = new SqlCommandBuilder(daSelectAll);
      daSelectAll.FillSchema(dsSelectAll,SchemaType.Mapped, "sample");
  
      foreach (string ri in temp1)
      {
          //for (int a3 = 0; a3 &lt; ssl.Count; a3++)
          {
  
  
                  cmdT.CommandText = @"SELECT * FROM [vijay].[dbo].[sample] where keyword in ('y','" + ri + "')";
                 // ds.Tables.Clear();
                  da.Fill(ds);
  
                  // row 1 ::     1   0   0   1   0   0
                  // row 2::      2   7   0   0   0   1   
  
                  int N00 = 0;
                  int N01 = 0;
                  int N10 = 0;
                  int N11 = 0;
  
                  for (int i = 0; i &lt; ds.Tables[0].Columns.Count; i++)
                  {
                      // N00
                      if (ds.Tables[0].Rows[0][i].ToString() == "0")
                      {
                          if (ds.Tables[0].Rows[1][i].ToString() == "0")
                          {
                              N00++;
                          }
                      }
  
                      // N01
                      if (ds.Tables[0].Rows[0][i].ToString() == "1")
                      {
                          if (ds.Tables[0].Rows[1][i].ToString() == "0")
                          {
                              N01++;
                          }
                      }
  
                      // N10
                      if (ds.Tables[0].Rows[0][i].ToString() == "0")
                      {
                          if ((ds.Tables[0].Rows[1][i].ToString()) !="0")
                          {
                              N10++;
                          }
                      }
  
                      // N11
                      if (ds.Tables[0].Rows[0][i].ToString() == "1")
                      {
                          if (ds.Tables[0].Rows[1][i].ToString()!="0")
                          {
                              N11++;
                          }
                      }
                  }
  
                  //if (a3 == (ssl.Count - 1))
                  {
                      //SqlCommand ins = new SqlCommand("update sample set N00=" + N00 + " where KeyWord='" + ri + "'", con);
                      //ins.ExecuteNonQuery();
  
                      DataRow[] drSelectAll = ds.Tables[0].Select("KeyWord='" + ri + "'");
                      drSelectAll[0]["N00"] = N00;
                      drSelectAll[0]["N01"] = N01;
                      drSelectAll[0]["N10"] = N10;
                      drSelectAll[0]["N11"] = N11;
  
  
                      double n = N00 + N11 + N10 + N01;
                      double w1 = Convert.ToDouble((N11 / n) * (Math.Log(((n * N11) / ((N10 + N11) * (N01 + N11))), 2)));
                      double w2 = Convert.ToDouble((N01 / n) * (Math.Log(((n * N01) / (((N01 + N00) * (N01 + N11)))), 2)));
                      double w4 = Convert.ToDouble((N00 / n) * (Math.Log(((n * N00) / (((N00 + N01) * (N00 + N10)))), 2)));
                      double w3 = Convert.ToDouble((N10 / n) * (Math.Log(((n * N10) / (((N10 + N11) * (N00 + N10)))), 2)));
                      if (w1.ToString() == "NaN")
                      {
                          w1 = 0;
                      }
                      if (w2.ToString() == "NaN")
                      {
                          w2 = 0;
                      }
                      if (w3.ToString() == "NaN")
                      {
                          w3 = 0;
                      }
                      if (w4.ToString() == "NaN")
                      {
                          w4 = 0;
                      }
  
                      double ni = w1 + w2 + w3 + w4;
  
                      drSelectAll[0]["MI"] = ni;
                      ds.Tables[0].Rows.Add(drSelectAll);
                  }
  
          }
      }
  
  
      try
      {
  
          daSelectAll.Update(ds, "sample");
  
      }
      catch (Exception)
      {
  
          throw;//error
      }
  </code></pre>
  
  <p>Error:Update unable to find TableMapping['sample'] or DataTable 'sample'.</p>