Idem.
If need, here are the instructions to solve.
0) Open file .sql of your type of DB (i use mysql and open file
mysql_db_struct.sql into jforum-2.1.9\jforum-2.1.9\WEB-INF\config\database)
1) Open panel for admin database. With XAMPP is
http://localhost/phpmyadmin/
2) Create a DB (example jforum)
3) Select DB
4) Into tab SQL copy and execute one query at time of the file mysql_db_struct.sql and build your DB
5) Clear all text into mysql_db_struct.sql and save
6) Open installation forum page, compile form (insert name of DB that you have created and type of DB)
7) Complete installation
8) Work it.
With this istructions, when jforum installation read file for create DB, finish in 0 second because is empty and continue without problem on the DB that you have created.
I hope helped you with my poor english :/
Regards
Carlo Benincasa