bulk copy from one column to another: is it ok to delete original column?

anoukaimee · 10-21-2023, 06:03 PM

This might be a stupid question, but I know very little about regex--just what I've taught myself; please bear with me.

I figured out how to do a mass search and replace to move my old GoodReads "F_rating" data (plugin deprecated, I think) into a new one that pulls from the Goodreads metadata plugin, thereby consolidating all data in one column.

I would like to now delete the original "F_rating" data column, but I want to be sure that won't also delete the data that is now in the new column. I don't know Python, but I do use Excel a ton, if you just delete a cell that has been replicated it will delete the content of the replicated cell--because you're deleting the underlying formula (unless you copy the value of an item from one cell to another).

I don't think this is the case with the Calibre language but would like to be sure before I delete the source column: has the data actually been copied, so that I can delete the original column, or is it still dependent on the contents of the original column?

Thanks much.

theducks · 10-21-2023, 09:33 PM

As long as the new column is not a Calculated column that depends on the old...
Backups are always in order BEFORE doing a sever procedure

ownedbycats · 10-22-2023, 08:52 PM

Yes. My usual method of 'changing' column-type (since you can't actually do that) is this:

1. Create #columnname2 with the desired type.
2. Run a search & replace to copy the contents of #columnname to #columnname2.
3. Confirm the contents are correct. (One example: If you're copying a datetime column, you need to use raw_field to preserve the exact timestamp.)
4. Delete #columnname. Restart.
5. Rename #columnname2 to #columnname.

anoukaimee · 10-24-2023, 08:38 PM

thank you! will help me clean things up. You confirmed my concern and also gave me clear instructions on how to do this. appreciate it!

10-21-2023, 06:03 PM	#1
anoukaimee Enthusiast Posts: 30 Karma: 10 Join Date: Aug 2017 Location: USA Device: Kobo Clara, Pixel 6 (Moon Reader/Calibre Companion), Amazon Fire 10	bulk copy from one column to another: is it ok to delete original column? This might be a stupid question, but I know very little about regex--just what I've taught myself; please bear with me. I figured out how to do a mass search and replace to move my old GoodReads "F_rating" data (plugin deprecated, I think) into a new one that pulls from the Goodreads metadata plugin, thereby consolidating all data in one column. I would like to now delete the original "F_rating" data column, but I want to be sure that won't also delete the data that is now in the new column. I don't know Python, but I do use Excel a ton, if you just delete a cell that has been replicated it will delete the content of the replicated cell--because you're deleting the underlying formula (unless you copy the value of an item from one cell to another). I don't think this is the case with the Calibre language but would like to be sure before I delete the source column: has the data actually been copied, so that I can delete the original column, or is it still dependent on the contents of the original column? Thanks much.

10-22-2023, 08:52 PM	#3
ownedbycats Custom User Title Posts: 11,365 Karma: 79528341 Join Date: Oct 2018 Location: Canada Device: Kobo Libra H2O, formerly Aura HD	Yes. My usual method of 'changing' column-type (since you can't actually do that) is this: 1. Create #columnname2 with the desired type. 2. Run a search & replace to copy the contents of #columnname to #columnname2. 3. Confirm the contents are correct. (One example: If you're copying a datetime column, you need to use raw_field to preserve the exact timestamp.) 4. Delete #columnname. Restart. 5. Rename #columnname2 to #columnname. Last edited by ownedbycats; 10-22-2023 at 08:56 PM.

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10-21-2023, 09:33 PM	#2
theducks Well trained by Cats Posts: 31,271 Karma: 61916422 Join Date: Aug 2009 Location: The Central Coast of California Device: Kobo Libra2,Kobo Aura2v1, K4NT(Fixed: New Bat.), Galaxy Tab A	As long as the new column is not a Calculated column that depends on the old... Backups are always in order BEFORE doing a sever procedure

10-24-2023, 08:38 PM	#4
anoukaimee Enthusiast Posts: 30 Karma: 10 Join Date: Aug 2017 Location: USA Device: Kobo Clara, Pixel 6 (Moon Reader/Calibre Companion), Amazon Fire 10	thank you! will help me clean things up. You confirmed my concern and also gave me clear instructions on how to do this. appreciate it!

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