C# how to prevent doublication while adding record using oledb : private void button1_Click(object sender, EventArgs e)
        {
            {

                System.Data.OleDb.OleDbConnection con = new System.Data.OleDb.OleDbConnection();
                con.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|\H3.mdb";

                con.Open();
                String DDate = DDD.Text.ToString();

                String my_querry = "INSERT INTO DailyReport(DDate)VALUES('" + DDate + "')";

                OleDbCommand cmd = new OleDbCommand(my_querry, con);
                cmd.ExecuteNonQuery();
                MessageBox.Show("Data saved successfuly...!");
                if(count>0)

                con.Close();
