Untitled

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.SqlClient;

namespace _5._11._21
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        SqlConnection con;
        SqlDataAdapter da;
        SqlCommand cmd;
        DataSet ds;

        void griddoldur()
        {
            con = new SqlConnection(@"Data Source = DESKTOP-8M7D7GE; Initial Catalog= yeni; User ID = sa;password=1234");
            da = new SqlDataAdapter("Select *From ogrenci", con);
            ds = new DataSet();
            con.Open();
            da.Fill(ds, "ogrenci");
            dataGridView1.DataSource = ds.Tables["ogrenci"];
            con.Close();

        }



        private void Form1_Load(object sender, EventArgs e)
        {
            griddoldur();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            cmd = new SqlCommand();
            con.Open();
            cmd.Connection = con;
            cmd.CommandText = "insert into ogrenci(ogrenci_no, ad, soyad, sehir) values ("+textBox1.Text + ",'" + textBox2.Text + "','" + textBox3.Text + "','" + textBox4.Text + "')";
            cmd.ExecuteNonQuery();
            con.Close();
            griddoldur();
        }

        private void button3_Click(object sender, EventArgs e)
        {
            cmd = new SqlCommand();
            con.Open();
            cmd.Connection = con;
            cmd.CommandText = "delete from ogrenci where ogrenci_no= " + textBox1.Text + "";
            cmd.ExecuteNonQuery();
            con.Close();
            griddoldur();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            cmd = new SqlCommand();
            con.Open();
            cmd.Connection = con;
            cmd.CommandText = "update ogrenci set ad='" + textBox2.Text + "',soyad='" + textBox3.Text + "',sehir='" + textBox4.Text + "'where ogrenci_no='" + textBox1.Text + "";
        }
    }
}