Nem mondom meg!

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;

namespace Adatbazis
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new frmBejelentkezes());
        }
    }
}
//2.


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;

namespace Adatbazis
{
    public partial class frmFoAblak : Form
    {
        private string user;
        private int restr;
        private string connection;

        public string Connection
        {
            get { return connection; }
            set { connection = value; }
        }

        public int Restr
        {
            get { return restr; }
            set { restr = value; }
        }

        public string User
        {
            get { return user; }
            set { user = value; }
        }

        public frmFoAblak()
        {
            InitializeComponent();
        }

        private void btnExit_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }

        private void frmFoAblak_FormClosing(object sender, FormClosingEventArgs e)
        {
            Application.Exit();
        }

        private void frmFoAblak_Shown(object sender, EventArgs e)
        {
            this.Text = "Nyilvántartás - " + User +
                " a bejelntkezett felhasználó";

            // ha csak sima felhasználó
            if (Restr == 2) {
                menuEgyesevel.Enabled = false;
                importálásToolStripMenuItem.Enabled = false;
            }
        }

        private void menuLista_Click(object sender, EventArgs e)
        {
            frmLista fLista = new frmLista();
            fLista.Connection = this.Connection;
            fLista.ShowDialog();
        }

        private void menuEgyesevel_Click(object sender, EventArgs e)
        {
            frmEgyes fEgyes = new frmEgyes();
            fEgyes.Connection = this.Connection;
            fEgyes.ShowDialog();
        }

        private void exportálásToolStripMenuItem_Click(object sender, EventArgs e)
        {
            frmExport fExport = new frmExport();
            fExport.Connection = this.Connection;
            fExport.ShowDialog();
        }

        private void importálásToolStripMenuItem_Click(object sender, EventArgs e)
        {
            frmImport fImport = new frmImport();
            fImport.Connection = this.Connection;
            fImport.ShowDialog();
        }
    }
}


//3.

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 MySql.Data.MySqlClient;

namespace Adatbazis
{
    public partial class frmBejelentkezes : Form
    {
        private string server = "localhost";
        private string uid = "root";
        private string password = "";
        private string database = "proba";
        private string connString = string.Empty;

        private MySqlConnection conn = null;
        private MySqlDataReader dr = null;

        public frmBejelentkezes()
        {
            InitializeComponent();
        }

        private void tbUser_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (e.KeyChar == (char) 13 )
            {
                tbPassword.Focus();
            }
        }

        private void tbPassword_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (e.KeyChar == (char) 13)
            {
                btnLogin.PerformClick();
            }
        }

        private void btnCancel_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }

        private void frmBejelentkezes_FormClosing(object sender, FormClosingEventArgs e)
        {
            Application.Exit();
        }

        private void frmBejelentkezes_Shown(object sender, EventArgs e)
        {
            tbUser.Focus();
        }

        private void btnLogin_Click(object sender, EventArgs e)
        {
            if (string.IsNullOrEmpty(tbUser.Text))
            {
                MessageBox.Show("Felhasználó nevet meg kell adni!",
                    "Hiba", MessageBoxButtons.OK,
                    MessageBoxIcon.Error);
                tbUser.Focus();
                return;
            }

            try
            {
                connString = string.Format(
                        "server={0};uid={1};password={2};database={3};",
                        server, uid, password, database
                    );
                conn = new MySqlConnection(connString);
                conn.Open();

                string select = "select * from users where user=\'" +
                    tbUser.Text + "\' and password=\'" + tbPassword.Text + "\'";
                MySqlCommand cmd = new MySqlCommand(select, conn);
                dr = cmd.ExecuteReader();
                int rows = 0;
                while (dr.Read())
                {
                    rows++;
                }
                if (rows > 0)
                {
                    //MessageBox.Show("Sikeres bejelentkezése!");
                    MessageBox.Show("Sikeres belépés!", "Információ",
                        MessageBoxButtons.OK, MessageBoxIcon.Information);
                    frmFoAblak f = new frmFoAblak();
                    f.User = tbUser.Text;
                    f.Connection = connString;
                    if (dr.GetInt32(3) == 1)
                    {
                        // admin
                        f.Restr = 1;
                        //MessageBox.Show("Admin");
                        f.BackColor = Color.Red;
                    }
                    else
                    {
                        // user
                        f.Restr = 2;
                        //MessageBox.Show("User");

                    }

                    f.Show();

                    this.Hide();
                }
                else
                {
                    MessageBox.Show("Sikertelen belépés!", "Hiba",
                        MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
            catch(MySqlException ex)
            {
                MessageBox.Show(ex.Message.ToString(), "Hiba",
                    MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            finally
            {
                if (dr != null)
                {
                    dr.Close();
                }

                if (conn != null)
                {
                    conn.Close();
                }
            }

        }
    }
}


//4.

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 MySql.Data.MySqlClient;

namespace Adatbazis
{
    public partial class frmEgyes : Form
    {
        private MySqlConnection conn = null;
        private MySqlDataAdapter da = null;
        private MySqlCommand mcd = null;
        private DataSet ds = null;
        private DataTable dt = new DataTable();
        private int i = 0;
        private string connection;

        public string Connection
        {
            get { return connection; }
            set { connection = value; }
        }

        public frmEgyes()
        {
            InitializeComponent();
        }

        public void Zarol()
        {
            btnModosit.Enabled = false;
            btnSzerkeszt.Enabled = false;
            btnTorol.Enabled = false;
            btnFel.Enabled = false;
        }

        public void labelNullazas()
        {
            tbVezeteknev.Text = "";
            tbKeresztnev.Text = "";
            tbTelefon.Text = "";
            tbEmail.Text = "";
            tbID.Text = "";
        }

        public void modMegnyit()
        {
            if (tbVezeteknev.ReadOnly == true)
            {
                tbVezeteknev.ReadOnly = false;
                tbKeresztnev.ReadOnly = false;
                tbTelefon.ReadOnly = false;
                tbEmail.ReadOnly = false;

                btnFirst.Enabled = false;
                btnLast.Enabled = false;
                btnRev.Enabled = false;
                btnFor.Enabled = false;

                btnModosit.Enabled = true;
                btnTorol.Enabled = true;
                btnFel.Enabled = true;
                btnLabelUres.Enabled = true;
            }
        }

        public void modBezar()
        {
            if (tbVezeteknev.ReadOnly == false)
            {
                tbVezeteknev.ReadOnly = true;
                tbKeresztnev.ReadOnly = true;
                tbTelefon.ReadOnly = true;
                tbEmail.ReadOnly = true;

                btnFirst.Enabled = true;
                btnLast.Enabled = true;
                btnRev.Enabled = true;
                btnFor.Enabled = true;

                btnModosit.Enabled = false;
                btnTorol.Enabled = false;
                btnFel.Enabled = false;
                btnLabelUres.Enabled = false;
            }
        }

        public void adatFrissit()
        {
            string select = "select * from names";

            ds = new DataSet();
            dt.Clear();
            da = new MySqlDataAdapter(select, conn);
            da.Fill(dt);
        }

        private void frmEgyes_Shown(object sender, EventArgs e)
        {
            conn = new MySqlConnection(this.Connection);
            try
            {
                string select = "select * from names";
                conn.Open();
                ds = new DataSet();
                da = new MySqlDataAdapter(select, conn);
                da.Fill(dt);
                // hibakezelés ha nincs benne adat
                ShowData();

                if (tbVezeteknev.Text == "")
                {
                    Zarol();
                }
            }
            catch (Exception)
            {

                throw;
            }
            btnModosit.Enabled = false;
            btnTorol.Enabled = false;
            btnFel.Enabled = false;
            btnLabelUres.Enabled = false;
        }

        private void btnVisszalepes_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        public void ShowData()
        {
            tbID.Text = dt.Rows[i][0].ToString();
            tbVezeteknev.Text = dt.Rows[i][1].ToString();
            tbKeresztnev.Text = dt.Rows[i][2].ToString();
            tbEmail.Text = dt.Rows[i][4].ToString();
            tbTelefon.Text = dt.Rows[i][3].ToString();
        }

        private void btnFirst_Click(object sender, EventArgs e)
        {
            i = 0;
            ShowData();
        }

        private void btnRev_Click(object sender, EventArgs e)
        {
            if (i != 0)
            {
                i--;
                ShowData();
            }
        }

        private void btnFor_Click(object sender, EventArgs e)
        {

            if (i < dt.Rows.Count - 1)
            {
                i++;
                ShowData();
            }
            else
            {
                MessageBox.Show("Vége");
            }
        }

        private void btnLast_Click(object sender, EventArgs e)
        {
            i = dt.Rows.Count - 1;
            ShowData();
        }

        private void btnSzerkeszt_Click(object sender, EventArgs e)
        {
            modMegnyit();
        }

        private void btnModosit_Click(object sender, EventArgs e)
        {
            string parancs = "update names set veznev='" + tbVezeteknev.Text + "', kernev='" + tbKeresztnev.Text + "', telefon='" + tbTelefon.Text + "', email='" + tbEmail.Text + "' where id=" + tbID.Text + "";
            mcd = new MySqlCommand(parancs, conn);
            if (mcd.ExecuteNonQuery() == 1)
            {
                MessageBox.Show("Siker");
                adatFrissit();
                modBezar();
            }
        }

        private void btnTorol_Click(object sender, EventArgs e)
        {
            string parancs = "delete from names where id=" +  tbID.Text + "";
            mcd = new MySqlCommand(parancs, conn);
            if (mcd.ExecuteNonQuery() == 1)
            {
                MessageBox.Show("Siker");
                labelNullazas();
                adatFrissit();
                modBezar();
            }
        }

        private void btnFel_Click(object sender, EventArgs e)
        {
            string parancs = "insert into `names` (`veznev`,`kernev`,`telefon`,`email`) values ('" + tbVezeteknev.Text + "','" + tbKeresztnev.Text + "','" + tbTelefon.Text + "','" + tbEmail.Text + "')";
            mcd = new MySqlCommand(parancs, conn);
            if (mcd.ExecuteNonQuery() == 1)
            {
                MessageBox.Show("Siker");
                labelNullazas();
                adatFrissit();
                modBezar();
            }
        }

        private void btnLabelUres_Click(object sender, EventArgs e)
        {
            labelNullazas();
        }

        private void btnMegse_Click(object sender, EventArgs e)
        {
            adatFrissit();
            modBezar();
        }
    }
}

//5.

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 MySql.Data.MySqlClient;
using System.IO;

namespace Adatbazis
{
    public partial class frmExport : Form
    {
        private MySqlConnection conn = null;
        private MySqlDataAdapter da = null;
        private MySqlCommand mcd = null;
        private DataSet ds = null;
        private DataTable dt = new DataTable();
        private int i = 0;
        private string connection;
        private FileStream file;
        private StreamWriter fileKi;

        public string Connection
        {
            get { return connection; }
            set { connection = value; }
        }

        public frmExport()
        {
            InitializeComponent();
        }

        private void frmExport_Shown(object sender, EventArgs e)
        {

        }

        private void btnKilep_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void btnExport_Click(object sender, EventArgs e)
        {
            try
            {
                if (saveDialog.ShowDialog() == DialogResult.OK)
                {
                    // adatbázis rész
                    conn = new MySqlConnection(this.Connection);

                    string select = "select * from names";
                    conn.Open();
                    ds = new DataSet();
                    da = new MySqlDataAdapter(select, conn);
                    da.Fill(dt);

                    // file rész
                    file = new FileStream(saveDialog.FileName, FileMode.Create);
                    fileKi = new StreamWriter(file);

                    for (int i = 0; i < dt.Rows.Count; i++)
                    {
                        string adat = "";

                        for (int j = 0; j < 5; j++)
                        {
                            if (j != 4)
                            {
                                adat += dt.Rows[i][j].ToString() + ",";
                            }
                            else
                            {
                                adat += dt.Rows[i][j].ToString();
                            }
                        }
                        fileKi.WriteLine(adat);
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
            finally
            {
                if (fileKi != null)
                {
                    fileKi.Close();
                    file.Close();
                    MessageBox.Show("Bezárva!");
                }
            }
        }
    }
}

//6.

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 MySql.Data.MySqlClient;

namespace Adatbazis
{
    public partial class frmLista : Form
    {
        private MySqlConnection conn = null;
        private MySqlDataAdapter da = null;
        private DataSet ds = null;

        private string connection;

        public string Connection
        {
            get { return connection; }
            set { connection = value; }
        }

        public frmLista()
        {
            InitializeComponent();
        }

        private void frmLista_FormClosing(object sender, FormClosingEventArgs e)
        {

        }

        private void btnClose_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void frmLista_Shown(object sender, EventArgs e)
        {
            conn = new MySqlConnection(this.Connection);
            try
            {
                string select = "select veznev, kernev, telefon, email from names";
                conn.Open();
                ds = new DataSet();
                da = new MySqlDataAdapter(select, conn);
                da.Fill(ds, "names");
                dgvAdatok.DataSource = ds.Tables["names"];
            }
            catch (Exception)
            {

                throw;
            }
        }
    }
}