How can I change default location for tablespaces In Oracle, how can I find out where datafiles for a tablespace are created by default if I do not provide a full path for the datafile but just the name?
And how can I change this default location?
show parameter db_create_file_dest will point to default datafile location.

To change default location execute this command

alter system set db_create_file_dest='target_dir' scope=both; 

(change is immediate no need to bounce the database)