Recommendation: use something like GIT (or one of the other fine source control systems out there) to checkpoint your work, and save the history of your org files. It can even be set up in emacs to periodically save all org files and check in a snapshot.
HTH,
Brian
From: Jude DaShiell <address@hidden>
To: address@hidden
Sent: Monday, July 18, 2011 4:36 PM
Subject: [O] feature request
A little data destruction protection. I put together a table and had to
destroy all copies of it after having tried to set up averages for a
couple columns. The averages didn't work and data got zeroed out and I
lost an entire column of data that way. One of my problems I'm sure was
caused because I tried data gathering first then tried modifying the
original table and adding the formulas later. Next time I attempt
anything with org and mathematics, I'll write my data set down in braille
and ought to have done that with this data set as well. What might have
helped here a little is if a column is going to be put into existing
columns the column inserts rather than overwrites any column that might be
there. The broken table I ended up with had six columns and two of those
were single space columns out to the right
with nothing in them. There
ought to have been before I did anything with formulas at most four
columns in the table. I did enter time stamps in as two separated date
and time fields originally then when I read what all could be put into
time stamps, I consolidated those first two columns into a single time
stamp column. I don''t know if that consolidation did further damage or
not.