Use the following code to update the value from datetime picker control to SQL QUERY
SqlCommand command = new SqlCommand();
SqlConnection connection = new SqlConnection();
connection.ConnectionString = "Valid connection";
connection.Open();
command.Connection = connection;
command.CommandText = "Insert into Sample values(1, 'kkk','" + dateTimePicker1.Value + "')";
command.ExecuteNonQuery();
As mentioned in the above code value from datetime picker control can be directly used in the sql query.