Prog Form C#

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 Npgsql;

namespace WindowsFormsApp2
{
    public partial class Prog : Form
    {
        public int n;
        NpgsqlConnection con = new NpgsqlConnection("Server=127.0.0.1;Port=5432;User Id=postgres;Password=12436Dark;Database=usersroles;");
        public Prog(int n)
        {
            InitializeComponent();
            con.Open();
            this.n = n;
            NpgsqlCommand com = new NpgsqlCommand("SELECT username FROM users WHERE userid = @num", con);
            com.Parameters.Add("num", NpgsqlTypes.NpgsqlDbType.Bigint).Value = n;
            string username = Convert.ToString(com.ExecuteScalar());
            lbUser.Text = username;
            NpgsqlCommand com1 = new NpgsqlCommand("SELECT first FROM users, buttonsaccess, roles WHERE userid = @num and roles.roleid = buttonsaccess.role and roles.roleid = users.role", con);
            com1.Parameters.Add("num", NpgsqlTypes.NpgsqlDbType.Bigint).Value = n;
            Boolean access1 = Convert.ToBoolean(com1.ExecuteScalar());
            if (access1 == false)
            {
                btFirst.Enabled = false;
            }
            NpgsqlCommand com2 = new NpgsqlCommand("SELECT second FROM users, buttonsaccess, roles WHERE userid = @num and roles.roleid = buttonsaccess.role and roles.roleid = users.role", con);
            com2.Parameters.Add("num", NpgsqlTypes.NpgsqlDbType.Bigint).Value = n;
            Boolean access2 = Convert.ToBoolean(com2.ExecuteScalar());
            if (access2 == false)
            {
                btSecond.Enabled = false;
            }
            NpgsqlCommand com3 = new NpgsqlCommand("SELECT third FROM users, buttonsaccess, roles WHERE userid = @num and roles.roleid = buttonsaccess.role and roles.roleid = users.role", con);
            com3.Parameters.Add("num", NpgsqlTypes.NpgsqlDbType.Bigint).Value = n;
            Boolean access3 = Convert.ToBoolean(com3.ExecuteScalar());
            if (access3 == false)
            {
                btThird.Enabled = false;
            }

            con.Close();
        }

        private void btFirst_Click(object sender, EventArgs e)
        {
            MessageBox.Show("Данный пользователь имеет доступ к функции 1","Кнопка 1", MessageBoxButtons.OK, MessageBoxIcon.Information);
            con.Open();
            string nowDate = DateTime.Now.ToShortDateString();
            string nowTime = DateTime.Now.ToShortTimeString();
            NpgsqlCommand cmd = new NpgsqlCommand("INSERT INTO \"journal\" (\"date\", \"time\", \"user\", \"action\") VALUES (@date, @time, @user, @act)", con);
            cmd.Parameters.Add("date", NpgsqlTypes.NpgsqlDbType.Date).Value = DateTime.Parse(nowDate);
            cmd.Parameters.Add("time", NpgsqlTypes.NpgsqlDbType.Time).Value = DateTime.Parse(nowTime);
            cmd.Parameters.Add("user", NpgsqlTypes.NpgsqlDbType.Bigint).Value = n;
            cmd.Parameters.Add("act", NpgsqlTypes.NpgsqlDbType.Bigint).Value = 2;
            cmd.ExecuteNonQuery();
            con.Close();

        }

        private void btSecond_Click(object sender, EventArgs e)
        {
            MessageBox.Show("Данный пользователь имеет доступ к функции 2", "Кнопка 2", MessageBoxButtons.OK, MessageBoxIcon.Information);
                con.Open();
            string nowDate = DateTime.Now.ToShortDateString();
            string nowTime = DateTime.Now.ToShortTimeString();
            NpgsqlCommand cmd = new NpgsqlCommand("INSERT INTO \"journal\" (\"date\", \"time\", \"user\", \"action\") VALUES (@date, @time, @user, @act)", con);
            cmd.Parameters.Add("date", NpgsqlTypes.NpgsqlDbType.Date).Value = DateTime.Parse(nowDate);
            cmd.Parameters.Add("time", NpgsqlTypes.NpgsqlDbType.Time).Value = DateTime.Parse(nowTime);
            cmd.Parameters.Add("user", NpgsqlTypes.NpgsqlDbType.Bigint).Value = n;
            cmd.Parameters.Add("act", NpgsqlTypes.NpgsqlDbType.Bigint).Value = 3;
            cmd.ExecuteNonQuery();
            con.Close();
        }

        private void btThird_Click(object sender, EventArgs e)
        {
            MessageBox.Show("Данный пользователь имеет доступ к функции 3", "Кнопка 3", MessageBoxButtons.OK, MessageBoxIcon.Information);
            con.Open();
            string nowDate = DateTime.Now.ToShortDateString();
            string nowTime = DateTime.Now.ToShortTimeString();
            NpgsqlCommand cmd = new NpgsqlCommand("INSERT INTO \"journal\" (\"date\", \"time\", \"user\", \"action\") VALUES (@date, @time, @user, @act)", con);
            cmd.Parameters.Add("date", NpgsqlTypes.NpgsqlDbType.Date).Value = DateTime.Parse(nowDate);
            cmd.Parameters.Add("time", NpgsqlTypes.NpgsqlDbType.Time).Value = DateTime.Parse(nowTime);
            cmd.Parameters.Add("user", NpgsqlTypes.NpgsqlDbType.Bigint).Value = n;
            cmd.Parameters.Add("act", NpgsqlTypes.NpgsqlDbType.Bigint).Value = 4;
            cmd.ExecuteNonQuery();
            con.Close();
        }

        private void button1_Click(object sender, EventArgs e)
        {

        }

        private void label2_Click(object sender, EventArgs e)
        {

        }

        private void lbUser_Click(object sender, EventArgs e)
        {


    }



        private void Prog_Load(object sender, EventArgs e)
        {

        }

        private void btBack_Click(object sender, EventArgs e)
        {
            con.Open();
            string nowDate = DateTime.Now.ToShortDateString();
            string nowTime = DateTime.Now.ToShortTimeString();
            NpgsqlCommand cmd = new NpgsqlCommand("INSERT INTO \"journal\" (\"date\", \"time\", \"user\", \"action\") VALUES (@date, @time, @user, @act)", con);
            cmd.Parameters.Add("date", NpgsqlTypes.NpgsqlDbType.Date).Value = DateTime.Parse(nowDate);
            cmd.Parameters.Add("time", NpgsqlTypes.NpgsqlDbType.Time).Value = DateTime.Parse(nowTime);
            cmd.Parameters.Add("user", NpgsqlTypes.NpgsqlDbType.Bigint).Value = n;
            cmd.Parameters.Add("act", NpgsqlTypes.NpgsqlDbType.Bigint).Value = 5;
            cmd.ExecuteNonQuery();
            this.Close();
            Form1 f1 = new Form1();
            f1.Show();
            con.Close();
        }
    }
}