Random function from specific sql table

I have to create a lottery program with c#.

Tables who I use is 3.

First table :Clients

Client_num   Client_Name    Client_ID

Second table: Prize

 Prize_Name  Prize_ID

3rd Table: Report

Prize_ID   Client_ID  ID_Number   --(who can be not unique).

My task is to create a form who visualize client num (between 1 to 435333, every months client num is differt, because i generated them from specific criteria).

For that I use select query in my code - who return the MAX ID from table Clents.

Except client num i have to visualize name of prize and this two rows have to visualize in report. My question is - How to create Random number between 1 to 435533 as these number to be a client num from "client" table in textbox - Client number.

Here is the code:

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        Random Lottery = new Random();

        SqlConnection con = new SqlConnection("Data Source=sqlsrvr;Initial Catalog=lottery;Integrated Security=True;");
        con.Open();
        SqlCommand cmd = new SqlCommand("SELECT MAX(id) AS ID FROM clients", con);
        cmd.ExecuteNonQuery();
        con.Close();
    }

    private void textBox1_TextChanged(object sender, EventArgs e)
    {

    }

    private void textBox3_TextChanged(object sender, EventArgs e)
    {

    }
}

}