org-table-copy-down for dates

Question

Suppose I have an org-table like this:

| 2018-09-09 |        |        |        |        |         
| 2018-09-10 |        |        |        |        |  
| 2018-09-11 |        |        |        |        |   
|          X |        |        |        |        |

X marks the location of the caret. If I invoke org-table-copy-down (shift+enter) 1998 will be inserted in the current cell. I suppose because 1998 = 2018-9-11. How can I get it to insert 2018-09-12 instead? I'm hoping that org-mode can be smart enough to understand that the column is about dates.

Answer 1

You have to mark them as dates: <2018-09-11>. See Dates and times. You can change the increment in the usual way, by customizing org-table-copy-increment which in the case of dates is in units of days.

EDIT: Here's an example as requested:

| Date             | what |
|------------------+------|
| <2018-10-01>     | foo  |
| X                | bar  |

With the cursor at X, pressing S-RET fills in the next day:

| Date             | what |
|------------------+------|
| <2018-10-01>     | foo  |
| <2018-10-02 Tue> | bar  |

More S-RET keep filling in more dates.

This assumes that org-table-copy-increment has the default value of t. If it is set to nil:

 #+begin_src emacs-lisp
 (setq org-table-copy-increment nil)
 #+begin_src emacs-lisp

then no increment is applied when you press S-RET and you get the same date that you started with.

If you set it to a number (e.g 2):

#+begin_src emacs-lisp
(setq org-table-copy-increment 2)
#+end_src

then S-RET incements by two days every time.

UPDATE: you can also use "inactive" dates like this [2018-10-01] with square brackets instead of angle brackets, but org mode needs some markup to recognize dates.