Preventing duplicated records

Question

Hi!

 

I wrote this codes for saving my records. But I dont want to see later my records repeated (or duplicated). How can I do to prevent it. When the same datas is already exist its should inform and refus. Save only when its doesnt exist in the database: 

...

public Form1()

{

InitializeComponent();

}

OleDbConnection conn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\WindowsFormsApplication1\App_data\test.mdb;Persist Security Info=False");

OleDbCommand comm;

string connstr = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\WindowsFormsApplication1\App_data\test.mdb;Persist Security Info=False";

private void button1_Click(object sender, EventArgs e)

{

conn = new OleDbConnection(connstr);

comm = new OleDbCommand();

conn.Open();

OleDbParameter name = new OleDbParameter("@name", SqlDbType.Date);

OleDbParameter fonction = new OleDbParameter("@fonction", SqlDbType.Date);

comm.Parameters.Add(name);

comm.Parameters.Add(fonction);

name.Value = textBox1.Text;

fonction.Value = textBox2.Text;

comm.Connection = conn;

comm.CommandText = "select count(*) from Not_duplicated_datas where name = @name";

int count = (int)comm.ExecuteScalar();

comm.ExecuteNonQuery();

conn.Close();

}