Zurückgeben von Nullwerten für den Zugriff auf die Datenbank über OleDb

Question

Ich habe eine INSERT-Anweisung eingerichtet, um Werte an die Datenbank zurückzugeben, wenn das Textfeld leer ist, aber immer noch nicht auf der Einfügung.

Ich habe festgestellt 'Kein Wert für einen oder mehrere Parameter angegeben.'

wohin gehe ich falsch?

meine Felder Zugang sind nicht gesetzt

erforderlich

private void NewCustomer_Load(object sender, EventArgs e) 
{ 

} 

private void button2_Click(object sender, EventArgs e) 
{ 
    OleDbConnection Conn = new OleDbConnection(); 
    Conn.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=BoilerSvc_be.mdb"; 
    OleDbCommand command = new OleDbCommand(); 
    command.CommandText = "INSERT INTO Contacts (Title,Initial,Surname,[Address 1],[Address 2],[Address 3],[Post Town],[Post Code],Telephone,Archived) VALUES (@Title,@FirstName,@LastName,@Address1,@Address2,@Address3,@PostTown,@PostCode,@Telephone,Archived = 0)"; 

    if (string.IsNullOrEmpty(FirstName.Text)) 
    { 
     command.Parameters.AddWithValue("@FirstName", DBNull.Value); 
    } 
    else 
    { 
     command.Parameters.AddWithValue("@FirstName", title.Text); 
    } 

    if (string.IsNullOrEmpty(LastName.Text)) 
    { 
     command.Parameters.AddWithValue("@LastName", DBNull.Value); 
    } 
    else 
    { 
     command.Parameters.AddWithValue("@LastName", title.Text); 
    } 

    if (string.IsNullOrEmpty(Address1.Text)) 
    { 
     command.Parameters.AddWithValue("@Address1", DBNull.Value); 
    } 
    else 
    { 
     command.Parameters.AddWithValue("@Address1", title.Text); 
    } 

    if (string.IsNullOrEmpty(Address2.Text)) 
    { 
     command.Parameters.AddWithValue("@Address2", DBNull.Value); 
    } 
    else 
    { 
     command.Parameters.AddWithValue("@Address2", title.Text); 
    } 

    if (string.IsNullOrEmpty(Address3.Text)) 
    { 
     command.Parameters.AddWithValue("@Address3", DBNull.Value); 
    } 
    else 
    { 
     command.Parameters.AddWithValue("@Address3", title.Text); 
    } 

    if (string.IsNullOrEmpty(Postcode.Text)) 
    { 
     command.Parameters.AddWithValue("@PostCode", DBNull.Value); 
    } 
    else 
    { 
     command.Parameters.AddWithValue("@PostCode", title.Text); 
    } 

    if (string.IsNullOrEmpty(TownCity.Text)) 
    { 
     command.Parameters.AddWithValue("@PostTown", DBNull.Value); 
    } 
    else 
    { 
     command.Parameters.AddWithValue("@PostTown", title.Text); 
    } 

    if (string.IsNullOrEmpty(PhnNum.Text)) 
    { 
     command.Parameters.AddWithValue("@Telephone", DBNull.Value); 
    } 
    else 
    { 
     command.Parameters.AddWithValue("@Telephone", title.Text); 
    } 

    if (string.IsNullOrEmpty(Titl.Text)) 
    { 
     command.Parameters.AddWithValue("@Title", DBNull.Value); 
    } 
    else 
    { 
     command.Parameters.AddWithValue("@Title", title.Text); 
    } 

    Conn.Open(); 
    command.Connection = Conn; 
    command.ExecuteNonQuery(); 
    Conn.Close(); 

    FirstName.Text = null; 
    LastName.Text = null; 
    Address1.Text = null; 
    Address2.Text = null; 
    Address2.Text = null; 
    Postcode.Text = null; 
    TownCity.Text = null; 
    Titl.Text = null; 
    PhnNum.Text = null; 
    Address3.Text = null; 

    MessageBox.Show("Customer Added"); 
} 

Answer 1

Basierend auf den Kommentaren Ich bin mir nicht sicher, ob dies mit einer OleDb-Verbindung funktioniert, aber Sie sollten Ihren Code wie folgt unter der Annahme, umschreiben es akzeptieren würde, die genannten Parameter.

private void button2_Click(object sender, EventArgs e) 
{ 
    using(OleDbConnection Conn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=BoilerSvc_be.mdb")) 
    { 
     OleDbCommand command = new OleDbCommand(); 

     command.CommandText = "INSERT INTO Contacts (Title,Initial,Surname,[Address 1],[Address 2],[Address 3],[Post Town],[Post Code],Telephone,Archived) VALUES (@Title,@FirstName,@LastName,@Address1,@Address2,@Address3,@PostTown,@PostCode,@Telephone,0)"; 

     command.Parameters.AddWithValue("@FirstName", string.IsNullOrEmpty(FirstName.Text) ? DBNull.Value : title.Text); 
     command.Parameters.AddWithValue("@LastName", string.IsNullOrEmpty(LastName.Text) ? DBNull.Value : title.Text); 
     command.Parameters.AddWithValue("@Address1", string.IsNullOrEmpty(Address1.Text) ? DBNull.Value : title.Text); 
     command.Parameters.AddWithValue("@Address2", string.IsNullOrEmpty(Address2.Text) ? DBNull.Value : title.Text); 
     command.Parameters.AddWithValue("@Address3", string.IsNullOrEmpty(Address3.Text) ? DBNull.Value : title.Text); 
     command.Parameters.AddWithValue("@PostCode", string.IsNullOrEmpty(Postcode.Text) ? DBNull.Value : title.Text); 
     command.Parameters.AddWithValue("@PostTown", string.IsNullOrEmpty(TownCity.Text) ? DBNull.Value : title.Text); 
     command.Parameters.AddWithValue("@Telephone", string.IsNullOrEmpty(PhnNum.Text) ? DBNull.Value : title.Text); 
     command.Parameters.AddWithValue("@Title", string.IsNullOrEmpty(Titl.Text) ? DBNull.Value : title.Text); 

     Conn.Open(); 
     command.Connection = Conn; 
     command.ExecuteNonQuery(); 
    } 

    FirstName.Text = null; 
    LastName.Text = null; 
    Address1.Text = null; 
    Address2.Text = null; 
    Address2.Text = null; 
    Postcode.Text = null; 
    TownCity.Text = null; 
    Title.Text = null; 
    PhnNum.Text = null; 
    Address3.Text = null; 

    MessageBox.Show("Customer Added"); 
} 

Answer 2

Wie bereits erwähnt, für OleDb Parameter Sie haben Fragen zu verwenden markiert statt:

private void button2_Click(object sender, EventArgs e) 
{ 
    try 
    { 
     using (var Conn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=BoilerSvc_be.mdb")) 
     { 
      var command = new OleDbCommand("INSERT INTO Contacts (" + 
           "Title, Initial, Surname,[Address 1],[Address 2],[Address 3],[Post Town],[Post Code],Telephone,Archived)" + 
         " VALUES ( ?,   ?,  ?,   ?,   ?,   ?,   ?,   ?,  ?,  0)", Conn); 
      Control[] controls = { Titl, FirstName, LastName, Address1, Address2, Address3, TownCity, Postcode, PhnNum }; 

      foreach (var control in controls) 
       command.Parameters.AddWithValue("@" + control.Name, 
        string.IsNullOrEmpty(control.Text) ? DBNull.Value : control.Text as object); 

      Conn.Open(); 
      if (command.ExecuteNonQuery() == 1) 
      { 
       MessageBox.Show("Customer Added"); 
       foreach (var control in controls) 
        control.Text = ""; 
      } 
      else 
       MessageBox.Show("Customer was not Added"); 

     } // Conn is closed and disposed at the end of the using block 
    } 
    catch (Exception ex) { 
     MessageBox.Show("Exception : " + ex.Message); 
    } 
}