insert data in sql table in C#

conn.Open();
cmd.Parameters.AddWithValue("@S_name", tbSupname.Text);
cmd.Parameters.AddWithValue("@P_billno", tbBILLNO.Text);
cmd.Parameters.AddWithValue("@P_ch_no", tbCHLNno.Text);
cmd.Parameters.AddWithValue("@P_pur_date", Convert.ToDateTime(dateTimePicker1.Text));
cmd.Parameters.AddWithValue("@P_btotal", tbtot1.Text);
cmd.Parameters.AddWithValue("@P_tovat", tbVAT.Text);
cmd.Parameters.AddWithValue("@P_dis", tbDisTOT.Text);
cmd.Parameters.AddWithValue("@P_gt", tbGT.Text);
cmd.ExecuteNonQuery();