is there a way to sort only on second level headlines in org mode?

Question

is there a way to sort only on second level headlines in org mode?

i am outlining a novel with top level headline being the chapter number and the second level headline being the timeline of the events in that chapter starting with a number = YYYYMMDD. the top level headline starts with a number representing the chapter. i have made the top level headline chapters high numbers in a hundreds sequence for ease of interpolating new chapters later, e.g., adding a chapter between 200 and the next chapter, 300, only requires adding at the end of the outline the new chapter with a top level headline of 250 and then resorting numerically. the second level headline is a different (chronological) number since chapter 300 may be a flashback occurring earlier in time than, say, chapter 100.

(see examples below)

if i could have two different ways of sorting (by chapter and by timeline), i could visualize the narrative more easily as i progress.

i have done some searching online for a solution and have considered tags and properties and functions but although i have been using emacs for about 5 years now (mainly as a text editor with .txt and .org and .markdown) formats, i am a writer with no programming or coding skills.

example of sorting by chapters (top level headline):

* 100 stranger comes to town
** 20190911
* 200 stranger meets chanteuse
** 20190925
* 300 stranger tells chanteuse a childhood story
** 19900525

example of sorting by timeline (second level headline):

* 300 stranger tells chanteuse a childhood story
** 19900525
* 100 stranger comes to town
** 20190911
* 200 stranger meets chanteuse
** 20190925

thanks for any help. i am not committed to org mode. any help will be appreciated. i could do this via a spreadsheet or a database manager, i realize, and have done so in the past, but would like to stay with emacs, which i use as aquamacs on an apple laptop.

Answer 1

As we have already discussed in the comments second level headings are probably the wrong structural means for an alternative sorting of the first level headings. There could be two subheadings 2.1, 2.2 below the second top-level heading 2. If the natural order of the subheadings is 2.1, 1.1, 2.2 the subheadings do not define an order-relation on the top-level headings. Thereby, your personal convention of only using one subheading per heading does not really play a big role. The ordering of the top-level headings w.r.t. the subheadings does not fit Org's structure. Therefore, you will have no special support for that purpose.

Org can sort headlines with respect to timestamps. That should perfectly fit your purpose.

Consider the following org file:

* 1
CLOCK: [2019-09-11 Wed]
Body of the first heading.
* 2
CLOCK: [2019-08-01 Thu]
Body of the second heading.
* 3
CLOCK: [2019-07-01 Mon]
Body of the third heading.

Select the whole file with C-x h and call M-x org-sort with choice t (standing for [t]ime) the file is modified as follows:

* 3
CLOCK: [2019-07-01 Mon]
Body of the third heading.
* 2
CLOCK: [2019-08-01 Thu]
Body of the second heading.
* 1
CLOCK: [2019-09-11 Wed]
Body of the first heading.

Side note: Trailing empty lines belong to the previous section. So if you have empty lines at the end of the file those move together with heading 3. Avoid such newlines to get a uniform appearance of the file sorted w.r.t. time.