I'm late i think :] soory,
If you are here like me searching for the solution when this error occurs with mysqldump instead of mysql, try this solution that i found on a german website out there by chance, so i wanted to share with homeless people who got headaches like me.
So the problem occurs because the lack -databases parameter before the database name
So your command must look like this:
mysqldump -pdbpass -udbuser --databases dbname
Another cause of the problem in my case was that i'm developping on local and the root user doesn't have a password, so in this case you must use --password= instead of -pdbpass, so my final command was:
mysqldump -udbuser --password= --databases dbname
Link to the complete thread (in German) : https://marius.bloggt-in-braunschweig.de/2016/04/29/solution-mysqldump-no-database-selected-when-selecting-the-database/
mysql -u root -p databasename < import.sql- Sam Dufel