How to show a error message if the data is already inserted in the database in c#
<pre><code>protected void Button2_Click(object sender, EventArgs e)
{
    SqlConnection conn = new SqlConnection("Data Source=KING;Initial Catalog=semasinter;Integrated Security=True");
    SqlCommand command = new SqlCommand("insert into StudentApplication", conn);
    command.CommandType = CommandType.StoredProcedure;
    command.CommandText = "spinsertstudentapplication";
    command.Parameters.AddWithValue("@Student_id", TextBox1.Text); 
    //command.Parameters.AddWithValue ("@Select_Course", ddlCourse.SelectedValue);
    command.Parameters.AddWithValue("@Select_Country", TextBox4.Text);
    command.Parameters.AddWithValue("@Select_State", TextBox2.Text);
    command.Parameters.AddWithValue("@Select_Franchise", TextBox3.Text);
    command.Parameters.AddWithValue("@Select_Sensei", ddlSensei.SelectedValue);
    command.Parameters.AddWithValue("@Group", TextBox6.Text);
    command.Parameters.AddWithValue("@Enter_Student_Name", TextBox7.Text);
    command.Parameters.AddWithValue("@Enter_Student_Address", TextBox8.Text);
    command.Parameters.AddWithValue("@Students_Father_Name", TextBox9.Text);
    command.Parameters.AddWithValue("@Student_DOB", TextBox10.Text);
    if (RadioButton2.Checked == true)
    {
        command.Parameters.Add("@Gender", SqlDbType.Bit).Value = true;

    }
    else
    {
        command.Parameters.Add("@Gender", SqlDbType.Bit).Value = false;

    }
    command.Parameters.Add("@Enter_Kyu", SqlDbType.NVarChar).Value = TextBox11.Text;       
    conn.Open();
    int rows = command.ExecuteNonQuery();   //// in these line i got a error message   
    conn.Close();

}
</code></pre>

<p>can u help me friends plz</p>
