Okay...
var x = DateTime.MinValue;
var b = DateTime.TryParse(txtcaldatetime.Text,out x);
x will now contain a valid datetime or DateTime.MinValue... Both of these you can write to your database.
C#
string sql = "insert into Tutor values(@tutorNumber, @studentNumber, @calDateTime, @timeSpent, @notes)";
SqlConnection connection = new SqlConnection();
SqlCommand command = new SqlCommand(sql, connection);
command.Parameters.Add(new SqlParameter {
ParameterName = "@Notes",
SqlDbType = SqlDbType.NVarChar,
Direction = ParameterDirection.Input,
Value = txtNotes.Text,
});
command.ExecuteNonQuery();
VB.NET
Dim sql As String = "insert into Tutor values(@tutorNumber, @studentNumber, @calDateTime, @timeSpent, @notes)"
Dim connection As New SqlConnection()
Dim command As New SqlCommand(sql, connection)
command.Parameters.Add(New SqlParameter() With { _
Key .ParameterName = "@Notes", _
Key .SqlDbType = SqlDbType.NVarChar, _
Key .Direction = ParameterDirection.Input, _
Key .Value = txtNotes.Text _
})
command.ExecuteNonQuery()