I have installed Oracle XE. I build small database every day to practice from command prompt, but now I want to have more. I want to have a bigger database with a lot of different data to practice and make exercises.
So, is possible to get a big data file from somewhere and upload to XE database?
As you are practicing with Oracle, perhaps a good solution (which will also generate exactly the data you need) would be to write your own stored procedures to generate your data in a loop (or similar construct). You could then generate as much as you like whilst also practicing your handling of large datasets and writing of efficient PL/SQL and SQL code.
This way your data will match your current database structure too without having to build a new database matching whichever dataset you download from the web.
IIRC there are sample schemas as HR that can be enabled. See this.
You can't get 'big' data for Oracle Express edition as it is limited to 4GB (10g) or 10GB (11g ).
That said, there are public datasets available. Personally I like the FAA data on registered aircraft owners/operators