C# Öğrenci Sınıf Yönetimi

Code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Configuration;
using System.Text;
using System.Windows.Forms;
using mysqlBaglantiNesnesi;
using System.Data.SqlClient;
using MySql.Data.MySqlClient;

namespace OgrenciSinifYonetimi
{
    public partial class OgrenciEkle : Form
    {
        mySqlBaglanti myBaglanti;
        string BaglantiMetni;
        string sqlText;
        MySqlConnection myCon;
        string secilenId;
        public OgrenciEkle()
        {
            InitializeComponent();
        }

        private void OgrenciEkle_Load(object sender, EventArgs e)
        {
            BaglantiMetni = ConfigurationSettings.AppSettings["baglantiMetni"];
            myBaglanti = new mySqlBaglanti(BaglantiMetni);
            myCon= new MySqlConnection(BaglantiMetni);
            ogrenciListesi();
        }

        private void yeniKayitButton_Click(object sender, EventArgs e)
        {
            sqlText = string.Format("INSERT INTO ogrenci(ogrenciad,ogrenciveliad,yas) VALUES('{0}','{1}','{2}');", textBox1.Text, textBox2.Text, comboBox1.Text);
            myBaglanti.baglantiAc();
            myBaglanti.SorguYaz(sqlText);
            myBaglanti.baglantiKapat();
            textTemizle();
            ogrenciListesi();
        }

        void textTemizle()
        {
            textBox1.Text = "";
            textBox2.Text = "";
            comboBox1.Text = "";
        }


        void ogrenciListesi()
        {
          sqlText="SELECT * FROM ogrenci";
          MySqlDataAdapter myDataAdapter = new MySqlDataAdapter(sqlText, myCon);
          DataTable myDataTable = new DataTable();
          myDataAdapter.Fill(myDataTable);
          dataGrid1.DataSource = myDataTable;
        }

        private void dataGrid1_CurrentCellChanged(object sender, EventArgs e)
        {
           secilenId = dataGrid1[dataGrid1.CurrentRowIndex, 0].ToString();
           textBox1.Text=dataGrid1[dataGrid1.CurrentRowIndex,1].ToString();
           textBox2.Text = dataGrid1[dataGrid1.CurrentRowIndex, 2].ToString();
           comboBox1.Text = dataGrid1[dataGrid1.CurrentRowIndex, 3].ToString();
        }

        private void KaydetButton_Click(object sender, EventArgs e)
        {
            sqlText = string.Format("Update ogrenci Set ogrenciad='{0}',ogrenciveliad='{1}',yas='{2}' WHERE ogrenciid={3}", textBox1.Text, textBox2.Text, comboBox1.Text,secilenId);
            myBaglanti.baglantiAc();
            myBaglanti.SorguYaz(sqlText);
            myBaglanti.baglantiKapat();
            textTemizle();
            ogrenciListesi();
        }

        private void silButton_Click(object sender, EventArgs e)
        {
            sqlText = string.Format("DELETE FROM ogrenci WHERE ogrenciid={0}",secilenId);
            myBaglanti.baglantiAc();
            myBaglanti.SorguYaz(sqlText);
            myBaglanti.baglantiKapat();
            textTemizle();
            ogrenciListesi();
        }
    }
}