C# ve SQL

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace WindowsApplication2
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

Hashtable universite = new Hashtable();
private void Form1_Load(object sender, EventArgs e)
{
label3.Text = universite.Count.ToString();
}

private void button1_Click(object sender, EventArgs e)
{
try
{
universite.Add(textBox1.Text, textBox2.Text);
listBox1.Items.Add(textBox1.Text);
label3.Text = universite.Count.ToString();
textBox1.Text = "";
textBox2.Text = "";
}

catch (SystemException)
{
label3.Text = "bu veri zaten var";
}
}

private void listBox1_DoubleClick(object sender, EventArgs e)
{
string deger;
deger = universite[listBox1.SelectedItem.ToString()].ToString();
MessageBox.Show(deger, listBox1.SelectedItem.ToString());
}

private void button3_Click(object sender, EventArgs e)
{
if (universite.Count == 0)
{
label3.Text = "dizide veri yok";
}
else if (listBox1.SelectedIndex == -1)
{
label3.Text = "öncelikle silinecek veri seçmelisin";
}
else
{
universite.Remove(listBox1.SelectedItem);
listBox1.Items.Remove(listBox1.SelectedItem);
label3.Text = "çıkartıldı";
label3.Text = universite.Count.ToString();
}
}

private void button2_Click(object sender, EventArgs e)
{
ICollection anahtar = universite.Keys;
foreach(string a in anahtar){
listBox2.Items.Add(a+"="+universite[a].ToString());
}
}
}
}