Incorrect syntax near 'achternaam'

Question

I am trying to insert a new row into a SQL Server table from a Winforms application. As far as I know my query is correct but Visual Studio keeps returning an error:

Incorrect syntax near 'achternaam'

I hope that someone can point me in the right direction.

public void UpdateGegevens(int id, string voornaam, string achternaam, string functie, DateTime geboortedatum, decimal uurloon)
{
if (ReturnFirstTime(id) == true)
{
    using (SqlConnection con = new SqlConnection(connectionString))
    {
        using (SqlCommand command = new SqlCommand())
        {
            command.Connection = con;
            command.CommandType = CommandType.Text;
            command.CommandText = "INSERT INTO tbl_Gegevens (Id, voornaam, achternaam, geboortedatum, functie, uurloon) VALUES (@Id, @vn, @an, @gb, @f, @ul);";

            command.Parameters.Add("@Id", SqlDbType.Int).Value = id;
            command.Parameters.Add("@vn", SqlDbType.VarChar).Value = voornaam;
            command.Parameters.Add("@an", SqlDbType.VarChar).Value = achternaam;
            command.Parameters.Add("@f", SqlDbType.VarChar).Value = functie;
            command.Parameters.Add("@gb", SqlDbType.Date).Value = geboortedatum;
            command.Parameters.Add("@ul", SqlDbType.Money).Value = uurloon;

            try
            {
                con.Open();
                command.ExecuteScalar();
            }
            catch (SqlException ex)
            {
                System.Windows.Forms.MessageBox.Show(ex.Message);
            }
            finally
            {
                con.Close();
            }
        }
    }
}
        else
        {
            using (SqlConnection con = new SqlConnection(connectionString))
            {
                using (SqlCommand command = new SqlCommand())
                {
                    command.Connection = con;
                    command.CommandType = CommandType.Text;
                    command.CommandText = "UPDATE tbl_Gegevens SET voornaam=@vn achternaam=@an geboortedatum=@gb funtie=@f uurloon=@ul WHERE Id = @Id;";
                    command.Parameters.AddWithValue("@Id", id);
                    command.Parameters.AddWithValue("@vn", voornaam);
                    command.Parameters.AddWithValue("@an", achternaam);
                    command.Parameters.AddWithValue("@gb", geboortedatum);
                    command.Parameters.AddWithValue("@f", functie);
                    command.Parameters.AddWithValue("@ul", uurloon);
                    try
                    {
                        con.Open();
                        command.ExecuteNonQuery();
                    }
                    catch (SqlException ex)
                    {
                        System.Windows.Forms.MessageBox.Show(ex.Message);
                    }
                    finally
                    {
                        con.Close();
                    }
                }
            }
        }
   }

Here is a specification of tbl_Gegevens:

create table [dbo].[tbl_Gegevens] (
   [Id] int not null
 , [voornaam] nvarchar(50) null
 , [achternaam] nvarchar(50) null
 , [geboortedatum] date null
 , [functie] nvarchar(50) null
 , [uurloon] smallmoney null
 , primary key clustered ([Id] asc)
 );

I think my dbms is ADO.Net.

This is the way i'm passing the info to the method:

private void btnConfirm_Click(object sender, EventArgs e)
    {
        if (tbName.Text != "" && tbSurname.Text != "" && tbFunction.Text
            != "" && dtpBirthdate.Value != date && nudSalary.Value != 0)
            {
                Database1.SetFirstTime(ID);
                Database1.UpdateGegevens(ID, tbName.Text, tbSurname.Text, tbFunction.Text, dtpBirthdate.Value, nudSalary.Value);
                this.Hide();
                frmMain fm = new frmMain(ID);
                fm.Show();
            }
            else
            {
                MessageBox.Show("Vul alle velden in!");
            }
        }

This is the query i use to get my id:

    public int ReturnLoginID(string username, string password)
    {
        SqlConnection con = new SqlConnection(connectionString);
        SqlCommand cmd = new SqlCommand("Select * from tbl_Login where UserName=@username and Password=@password", con);
        cmd.Parameters.AddWithValue("@username", username);
        cmd.Parameters.AddWithValue("@password", password);
        int ID = 9999;
        con.Open();
        using (SqlDataReader reader = cmd.ExecuteReader())
        {
            reader.Read();
            ID = reader.GetInt32(0);
        }
        con.Close();
        return ID;
    }

Answer 1

In the UPDATE part of your code there are no commas to separate the fields in the SET list

command.CommandText = @"UPDATE tbl_Gegevens SET voornaam=@vn,
                       achternaam=@an, geboortedatum=@gb, 
                       funtie=@f, uurloon=@ul WHERE Id = @Id;";

I think that this question could be used to underline the importance of using a debugger. This problem would be solved much sooner if you had stepped through your code using the debugger.