Notes

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.OleDb;
namespace quiztekrarhh
{
public partial class Form1 : Form
{
OleDbConnection baglanti = new OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=quizdatabase.accdb");
public Form1()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
baglanti.Open();
OleDbCommand aksesuaridalmakodu = new OleDbCommand("select * from aksesuartbl where Adi='" + comboBox1.SelectedItem.ToString() + "'", baglanti);
OleDbDataReader aksesuaridoku = aksesuaridalmakodu.ExecuteReader();
int aksesuarid = 0;
int fiyatid = 0;
if (aksesuaridoku.Read())
{
aksesuarid = Convert.ToInt16(aksesuaridoku["Aksesuar_ID"].ToString());
fiyatid = Convert.ToInt16(aksesuaridoku["Fiyat"].ToString());

}

OleDbCommand firmabilgilerikodu = new OleDbCommand("select * from firmalartbl where Aksesuar_ID=" + aksesuarid, baglanti);
OleDbDataReader bilgigetir = firmabilgilerikodu.ExecuteReader();
string firmaadi = "";
int stok = 0;
while (bilgigetir.Read())
{
firmaadi = bilgigetir["Adi"].ToString();
stok = Convert.ToInt16(bilgigetir["Stok_ID"].ToString());
listBox1.Items.Add(comboBox1.SelectedItem.ToString() + " " + firmaadi + " " + fiyatid + " " + stok);
}

baglanti.Close();
}

private void Form1_Load(object sender, EventArgs e)
{
baglanti.Open();

OleDbCommand aksesuargetir = new OleDbCommand("SELECT aksesuartbl.Adi FROM aksesuartbl", baglanti);
OleDbDataReader getir = aksesuargetir.ExecuteReader();
while (getir.Read())
{
comboBox1.Items.Add(getir["Adi"].ToString());
}
baglanti.Close();
}

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
baglanti.Open();
/* SEÇİLEN AKSESUARIN ID'SİNİ ALMAK İÇİN YAZDIĞIMIZ KOD*/
OleDbCommand aksesuaridgetirkomutu = new OleDbCommand("select Aksesuar_ID from aksesuartbl where Adi='" + comboBox1.SelectedItem.ToString()+"'", baglanti);
OleDbDataReader oku = aksesuaridgetirkomutu.ExecuteReader();
int id = Convert.ToInt16(oku.Read());
/* O AKSESUAR IDSİNE SAHİP FİRMALARIN ADLARINI ÇEKECEĞİZ.*/
OleDbCommand firmalarigetirmekomutu = new OleDbCommand("select * from firmalartbl where Aksesuar_ID="+id, baglanti);
OleDbDataReader oku2 = firmalarigetirmekomutu.ExecuteReader();
while (oku2.Read())
{
comboBox3.Items.Add(oku2["Adi"].ToString());
}
baglanti.Close();
}

private void button3_Click(object sender, EventArgs e)
{
listBox1.Items.Clear();
baglanti.Open();
OleDbCommand getir = new OleDbCommand("select * from firmalartbl where Adresi='" + textBox1.Text + "'", baglanti);
OleDbDataReader oku = getir.ExecuteReader();
while (oku.Read())
{
listBox1.Items.Add(oku["Adi"].ToString());
}
baglanti.Close();
}

private void button4_Click(object sender, EventArgs e)
{
baglanti.Open();
OleDbCommand getir = new OleDbCommand("select * from aksesuartbl where Fiyat>'" + textBox2.Text + "' and Fiyat<'" + textBox3.Text+"'", baglanti);
OleDbDataReader oku = getir.ExecuteReader();
while (oku.Read())
{
listBox1.Items.Add(oku["Adi"].ToString() +" "+ oku["Fiyat"].ToString());
}
baglanti.Close();
}

private void button2_Click(object sender, EventArgs e)
{
baglanti.Open();
OleDbCommand aksesuaridgetirkomutu = new OleDbCommand("select Aksesuar_ID from aksesuartbl where Adi='" + comboBox1.SelectedItem.ToString() + "'", baglanti);
OleDbDataReader oku = aksesuaridgetirkomutu.ExecuteReader();
int id = Convert.ToInt16(oku.Read());

OleDbCommand firmabilgilerigetirmekodu = new OleDbCommand("select * from firmalartbl where Aksesuar_ID=" + id, baglanti);
OleDbDataReader getir = firmabilgilerigetirmekodu.ExecuteReader();
while (getir.Read())
{
listBox1.Items.Add(getir["Adi"].ToString() + " " + getir["Telefon_Numarasi"].ToString() + " " + getir["Adresi"].ToString());
}
baglanti.Close();
}

private void button5_Click(object sender, EventArgs e)
{
Form2 ikinciform = new Form2();
ikinciform.ShowDialog();
}
}
}
------------ FORM 2 ------------

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.OleDb;
namespace quiztekrarhh
{
public partial class Form2 : Form
{
OleDbConnection baglanti = new OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=quizdatabase.accdb");
public Form2()
{
InitializeComponent();
}

private void Form2_Load(object sender, EventArgs e)
{
baglanti.Open();

OleDbCommand aksesuargetir = new OleDbCommand("SELECT * FROM aksesuartbl", baglanti);
OleDbDataReader getir = aksesuargetir.ExecuteReader();
while (getir.Read())
{
comboBox1.Items.Add(getir["Adi"].ToString());
comboBox2.Items.Add(getir["Adi"].ToString());
}
comboBox1.SelectedIndex = comboBox2.SelectedIndex = 0;
baglanti.Close();
}

private void button5_Click(object sender, EventArgs e)
{
baglanti.Open();
OleDbCommand silmekomutu = new OleDbCommand("delete from aksesuartbl where Adi='" + comboBox1.SelectedItem.ToString() + "'", baglanti);
silmekomutu.ExecuteNonQuery();
baglanti.Close();
MessageBox.Show("VERI SİLİNDİ!");
}

private void button1_Click(object sender, EventArgs e)
{
baglanti.Open();
OleDbCommand eklemekomutu = new OleDbCommand("insert into aksesuartbl (Adi) values(@adi)", baglanti);
eklemekomutu.Parameters.AddWithValue("@adi", textBox1.Text);
eklemekomutu.ExecuteNonQuery();
MessageBox.Show("VERI EKLENDI!");
baglanti.Close();
}
}
}