title: insert to the dbf file does not accept null values
body: <p>I've got a dbf file which I want to execute query. This is my code (.net 4.0, C# Windows Forms):</p>
  
  <pre><code>oconn.ConnectionString = "Provider=vfpoledb.1;Data Source=" + path + ";Collating Sequence=machine";
  oconn.Open();
  OleDbCommand ocmd = oconn.CreateCommand();
  string na = TBNazwaKonta.Text.Replace("\n","");
  na = na.Replace("\r","") ;
  string ks2 = ks.Replace("\n","");
  ks2 = ks2.Replace("\r", "");
  string zapytanie = @"insert into " + path + " (rk, Na,Ks,Ss,So,Wyr,Bw,Bm,Ow,Om,Wm,Mm,Pm,Pw,Ks1,Ks2,Ks3,Ks4,Llx,Wn01,Ma01,L01,Wn02,Ma02,L02,Wn03,Ma03,L03,Wn04,Ma04,L04,Wn05,Ma05,L05,Wn06,Ma06,L06,Wn07,Ma07,L07,Wn08,Ma08,L08,Wn09,Ma09,L09,Wn10,Ma10,L10,Wn11,Ma11,L11,Wn12,Ma12,L12) values (0,'Z-Dz PROD.OPAKOWAŃKIEWICZA 108   38-200 ', '200 02 000212',0,0,'',0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,'','','','',0,0.0,0.0,0,0.0,0.0,0,0.0,0.0,0,0.0,0.0,0,0.0,0.0,0,0.0,0.0,0,0.0,0.0,0,0.0,0.0,0,0.0,0.0,0,0.0,0.0,0,0.0,0.0,0,0.0,0.0,0)";
  ocmd.CommandText = zapytanie;
  ocmd.ExecuteNonQuery();
  oconn.Close();
  </code></pre>
  
  <p>Connection is fine, insert query is fine too, but I want to know why this dbf does not accept null values.  </p>
  
  <p>Where could I check that dbf accepts nulls? When I using an program to read dbfs and I execute a query then dbf accepts null. It not accept only when I use ado.net. 
  Thanks for any help solving my problem</p>