Запись данных в базу

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.OleDb;
using System.Text.RegularExpressions;
 
namespace lamps
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
 
        private void button1_Click(object sender, EventArgs e)
        {
            string digits_num_lamp = textBox1.Text;
            string Combo2text = comboBox2.Text;
            try
            {
                Regex r = new Regex(@"\d");
                Match m = r.Match(digits_num_lamp);
                if (((digits_num_lamp != "") & (m.Success)) & (comboBox2.SelectedIndex != -1))
                {
                    string sql = "INSERT INTO fix(num_lamp, type_repair)" +
                                        "VALUES(" + digits_num_lamp + "," + Combo2text + ")";
 
                    string connectionString;
                    DataTable dataTable = new DataTable();
                    DataGridView dataGridView = new DataGridView();
                    connectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Lamps.mdb;Jet OLEDB:Engine Type=5;Jet OLEDB:Database Password=Пароль";
                    OleDbConnection connection = new OleDbConnection(connectionString);
                    connection.Open();
                    OleDbCommand OleDbCommand = new OleDbCommand(sql, connection);
                    OleDbDataAdapter dataAdapter = new OleDbDataAdapter(OleDbCommand);
                    OleDbCommandBuilder commandBuilder = new OleDbCommandBuilder(dataAdapter);
                    //dataAdapter.Fill(dataTable);
                    //dataGridView.DataSource = dataTable;
                    //dataAdapter.Update((DataTable)dataGridView.DataSource);
                    OleDbCommand.ExecuteNonQuery();
                    connection.Close();
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show("Ошибка: " + ex.Message);
            }
 
        }
    }
}

DataGridView dataGridView = new DataGridView();
                    connectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Lamps.mdb;Jet OLEDB:Engine Type=5;Jet OLEDB:Database Password=Пароль";
                    OleDbConnection connection = new OleDbConnection(connectionString);
                    connection.Open();
                    OleDbCommand OleDbCommand = new OleDbCommand(sql, connection);
string sql = "INSERT INTO fix([num_lamp], [type_repair])" +
                                        "VALUES(@textbox, @combobox)";
OleDbCommand.Parameters.AddWithValue("@textbox", digits_num_lamp.Text);
OleDbCommand.Parameters.AddWithValue("@combobox", Combo2text.Text);
int ui = OleDbCommand.ExecuteNonQuery();
            conn.Close();

                    DataGridView dataGridView = new DataGridView();
                    string connectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Lamps.mdb;Jet OLEDB:Engine Type=5;Jet OLEDB:Database Password=Пароль";
                    OleDbConnection connection = new OleDbConnection(connectionString);
                    connection.Open();
                    string sql = "INSERT INTO fix([num_lamp], [type_repair])" +
                                        "VALUES(@textbox, @combobox)";
                    OleDbCommand OleDbCommand = new OleDbCommand(sql, connection);
                    OleDbCommand.Parameters.AddWithValue("@textbox", digits_num_lamp);
                    OleDbCommand.Parameters.AddWithValue("@combobox", Combo2text);
                    OleDbCommand.ExecuteNonQuery();
                    connection.Close();

                    OleDbCommand OleDbComm = new OleDbCommand(sql, connection);
                    OleDbComm.Parameters.AddWithValue("@textbox", digits_num_lamp);
                    OleDbComm.Parameters.AddWithValue("@combobox", Combo2text);
                    OleDbComm.ExecuteNonQuery();