You can specify the database name as a literal, a local variable, or a parameter to a stored procedure.
The database must exist. You can create a database with the for load option of create database, or load it over an existing database. Loading a database always overwrites all the information in the existing database.
You do not need to use the same database name as the name of the database you dumped. For example, you can dump the pubs2 database, create another database called pubs2_archive, and load the dump into the new database.