Método 1:

1. Cambiar codificación a la Base de datos
2. mysqldump --default-character-set=latin1 -u root -p DBNAME TABLENAME 
> /tmp/TABLENAME-YYYYMMDD.sql
3. Editar "DEFAULT CHARSET=latin1" y "/*!40101 SET NAMES latin1*/" a utf8.
4. Ejecutar el archivo SQL

Método 2:

DB="nombre BBDD"
(
    echo 'ALTER DATABASE `'"$DB"'` CHARACTER SET utf8 COLLATE utf8_general_ci;'
    mysql "$DB" -e "SHOW TABLES" --batch --skip-column-names \
    | xargs -I{} echo 'ALTER TABLE `'{}'` CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;'
) \
| mysql "$DB"

Ref:

http://stackoverflow.com/questions/6115612/how-to-convert-an-entire-mysql-database-characterset-and-collation-to-utf-8

https://ociotec.com/convertir-bd-en-mysql-de-latin1-a-utf8/

http://stackoverflow.com/questions/6115612/how-to-convert-an-entire-mysql-database-characterset-and-collation-to-utf-8