Query empty fields

FrancoisFrancois · 09-28-2025, 05:28 AM

Hello

With Calibre, we can query different fields.
I'm trying to query empty fields.
For example, I want to list all the books whose Author(s) field is empty. I can't find the correct syntax.
Can someone help me?

See you soon.

chaley · 09-28-2025, 08:21 AM

Moderator Notice
Moved from recipes to library management.

chaley · 09-28-2025, 08:24 AM

It would be "authors:false" if the authors field could ever be empty, which it can't. A book must always have an author. In English the author is set to "Unknown" if one isn't provided.

FrancoisFrancois · 10-03-2025, 02:16 AM

Hello

Thank you very much for this reply.
I tested it with false on random fields and it works. It's GREAT.

Indeed, querying empty Author fields doesn't make sense.
I should have indicated the field I wanted to query right away. It's the comment field. I tried "comment" or "comments" but it didn't work. I can't find the exact comment name to find books without comments.

Any ideas?

See you soon.

Karellen · 10-03-2025, 02:46 AM

Should be comments:false

You can find the correct names in Preferences>Look&Feel>Book Details. It will be the name in brackets.

09-28-2025, 05:28 AM	#1
FrancoisFrancois Junior Member Posts: 4 Karma: 10 Join Date: Aug 2018 Device: Calibre	Query empty fields Hello With Calibre, we can query different fields. I'm trying to query empty fields. For example, I want to list all the books whose Author(s) field is empty. I can't find the correct syntax. Can someone help me? See you soon.

10-03-2025, 02:46 AM	#5
Karellen Wizard Posts: 1,654 Karma: 9500498 Join Date: Sep 2021 Location: Australia Device: Kobo Libra 2	Should be comments:false You can find the correct names in Preferences>Look&Feel>Book Details. It will be the name in brackets. Attached Thumbnails

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09-28-2025, 08:21 AM	#2
chaley Grand Sorcerer Posts: 12,524 Karma: 8065948 Join Date: Jan 2010 Location: Notts, England Device: Kobo Libra 2	Moderator Notice Moved from recipes to library management.

09-28-2025, 08:24 AM	#3
chaley Grand Sorcerer Posts: 12,524 Karma: 8065948 Join Date: Jan 2010 Location: Notts, England Device: Kobo Libra 2	It would be "authors:false" if the authors field could ever be empty, which it can't. A book must always have an author. In English the author is set to "Unknown" if one isn't provided.

10-03-2025, 02:16 AM	#4
FrancoisFrancois Junior Member Posts: 4 Karma: 10 Join Date: Aug 2018 Device: Calibre	Hello Thank you very much for this reply. I tested it with false on random fields and it works. It's GREAT. Indeed, querying empty Author fields doesn't make sense. I should have indicated the field I wanted to query right away. It's the comment field. I tried "comment" or "comments" but it didn't work. I can't find the exact comment name to find books without comments. Any ideas? See you soon.