protected void Button1_Click(object sender, EventArgs e)
{
    string myConnection = "datasource=blahblah;port=blahblah;username=blahblah;password=blahblah";
    MySqlConnection con = new MySqlConnection(myConnection);
    MySqlCommand cmd = new MySqlCommand("SELECT * FROM purchase_history_table WHERE student_id LIKE   '%" + this.TextBoxstudentid.Text + "%' ;", con);
    DataTable dt1 = new DataTable();
    MySqlDataAdapter adp = new MySqlDataAdapter(cmd);
    adp.Fill(dt1);
    GridView1.DataSource = dt1;
    GridView1.DataBind();
}