I recently had to extract a database from a full backup, I only needed one database hardly 1MB in size but the whole backup exceeded 3GB and didn’t want to import all of it. Below is the command I found to make it work
First make a empty database with the same name you want to extract
CREATE DATABASE dbname;
Exit and run the following:
mysql -u root -p --one-database dbname < alldb.sql
Voila! you’re done.