ถามเรื่อง การใช้งาน Autocomplete ใน Windows Forms แบบดึงข้อมูลจาก database ทำอย่าไรครับ c# (มีรูปให้ดู)

private void textBox5_TextChanged(object sender, EventArgs e)
        {
            string sql = "Select DocName FROM tblDoctor";
            SqlCommand commandSelectDocName = new SqlCommand(sql,connection);
            SqlDataReader readerDocNameFromtblDoctor=commandSelectDocName.ExecuteReader();

            AutoCompleteStringCollection autoDocNameFromtblDoctor = new AutoCompleteStringCollection();
            while (readerDocNameFromtblDoctor.Read())
            {
                autoDocNameFromtblDoctor.Add(readerDocNameFromtblDoctor["DocName"]);
            }
        }

autoDocNameFromtblDoctor.Add(readerDocNameFromtblDoctor["DocName"].ToString());

 SqlConnection CN;
        DataSet DSA = new DataSet();
        SqlDataAdapter DAA;
  private void Form1_Load(object sender, EventArgs e)
        {

   CN = new SqlConnection();
                CN.ConnectionString = "data source = VII5RI-PC01\\SA; initial catalog=ALZDATA; user id=sa; password=123";
                string SQL = "select * from tblPatient";
                DAA = new SqlDataAdapter(SQL, CN);
                SqlCommandBuilder CB = new SqlCommandBuilder(DAA);
                DAA.Fill(DSA, "PATAlz");
}