Temat: [C#, SQL] Aplikacja obsługująca bazę danych

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace Dziennikv3
{
    public partial class pokazOcenyForm : Form
    {

        SqlConnection cn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\Maciej\Desktop\ZABAWA WCIAZ TRWA\v3\Dziennikv3\Dziennikv3\db9.mdf;Integrated Security=True;User Instance=True");
        SqlCommand cmd = new SqlCommand();
        SqlDataReader dr;

        public pokazOcenyForm()
        {
            InitializeComponent();
        }

        private void pokazOcenyForm_Load(object sender, EventArgs e)
        {
             
        }

        private void button1_Click(object sender, EventArgs e)
        {
            cmd.Connection = cn;
            listBox1.Items.Clear();
            listBox2.Items.Clear();
            cn.Open();
            cmd.CommandText = "select IDucznia, Ocena from tableOcen";
            dr = cmd.ExecuteReader();
            if (dr.HasRows)
            {
                while (dr.Read())
                {
                    listBox1.Items.Add(dr[0].ToString());
                    listBox2.Items.Add(dr[1].ToString());
                }
            }
            cn.Close();
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace Dziennikv3
{
    public partial class dodajOcenyForm : Form
    {
        SqlConnection cn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\Maciej\Desktop\ZABAWA WCIAZ TRWA\v3\Dziennikv3\Dziennikv3\db9.mdf;Integrated Security=True;User Instance=True");
        SqlCommand cmd = new SqlCommand();

        public dodajOcenyForm()
        {
            InitializeComponent();
        }

        private void dodajOcenyForm_Load(object sender, EventArgs e)
        {
            cmd.Connection = cn;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (IDo.Text != "" & IDu.Text != "" & OCE.Text != "" )
            {
                cn.Open();

                
                cmd.CommandText = "SET IDENTITY_INSERT tableOcen ON";
                cmd.CommandText = "insert into tableOcen (IDocena, Ocena, IDucznia) values ('" + IDo.Text + "', '" + OCE.Text + "', '" + IDu.Text + "')";
                cmd.CommandText = "SET IDENTITY_INSERT tableOcen OFF";
                cmd.ExecuteNonQuery();
                cmd.Clone();
                const string message = "Ocena dodana pomyslnie.";
                const string caption = "";
                var result = MessageBox.Show(message, caption,
                                             MessageBoxButtons.OK);
                cn.Close();

                IDo.Text = "";
                IDu.Text = "";
                OCE.Text = "";
             }
            else
            {
                const string message = "Nie udalo sie dodac oceny. Prosimy wypelnic wymagane pola: ID Oceny, ID ucznia, ocene i przedmiot.";
                const string caption = "";
                var result = MessageBox.Show(message, caption,
                                             MessageBoxButtons.OK);
            }
        }

private void listBox2_SelectedIndexChanged(object sender, EventArgs e)
        {
            ListBox l = sender as ListBox;
            if (l.SelectedIndex != -1)
            {
                listBox1.SelectedIndex = l.SelectedIndex;
                listBox2.SelectedIndex = l.SelectedIndex;
            }
        }
      
    }
}