How to insert the XML file in DB

Question

How to insert this XML file in SQL Server? I have done one but cannot output. The error said "String was not recognized as a valid DateTime"

 

Here the code that I done:

SqlDataAdapter adpter = new SqlDataAdapter();
DataSet ds = new DataSet();
int appointment_ID = 0;
string nric = null;
string client_Name = null;
DateTime? appointment_Date = null;
DateTime? start_Time = null;
SqlConnection conn = new SqlConnection(@"Data Source=USER1-PC\SQLEXPRESS;Integrated Security=true;Database=ProductDB");
XmlReader xmlFile = XmlReader.Create("G://appointment.xml", new XmlReaderSettings());
ds.ReadXml(xmlFile);
int i = 0;
conn.Open();
for (i = 0; i <= ds.Tables[0].Rows.Count - 1; i++)
{
appointment_ID = Convert.ToInt32(ds.Tables[0].Rows[i].ItemArray[0]);
appointment_Date = DateTime.Parse(ds.Tables[0].Rows[i].ItemArray[1].ToString());
start_Time = DateTime.Parse(ds.Tables[0].Rows[i].ItemArray[2].ToString());
nric = ds.Tables[0].Rows[i].ItemArray[3].ToString();
client_Name = ds.Tables[0].Rows[i].ItemArray[4].ToString();
SqlCommand command = new SqlCommand("insert into Appointment values(" + appointment_ID + ",'" + appointment_Date + "'," + start_Time + "'," + nric + "'," + client_Name + ")", conn);
adpter.InsertCommand = command;
adpter.InsertCommand.ExecuteNonQuery();
}
conn.Close();
MessageBox.Show("Done .. ");

Here is appointment.xml:

<Interface>
<Appointment>
<Appointment_ID> 000000087508</Appointment_ID>
<Appointment_Date>2018-01-25</Appointment_Date>
<Appointment_Start_Time>13:15:00</Appointment_Start_Time>
<Client>
<NRIC>456987123</NRIC>
<Client_Name>JAMES</Client_Name>
</Client>
</Appointment>
<Appointment>
<Appointment_ID>000000087501</Appointment_ID>
<Appointment_Date>2018-01-25</Appointment_Date>
<Appointment_Start_Time>14:30:00</Appointment_Start_Time>
<Client>
<NRIC>963258741</NRIC>
<Client_Name>Bill Tan</Client_Name>
</Client>
<Client>
<NRIC>123456789</NRIC>
<Client_Name>David Ang</Client_Name>
</Client>
</Appointment>
<Checksum>2</Checksum>
</Interface>