How to determine who is and change the owner of database?
Use the following query:
SELECT DISTINCT RDB$OWNER_NAME AS DATABASE_OWNER
WHERE (RDB$SYSTEM_FLAG = 1);
Please note that in order to change the owner, it is not enough (or even advisable) to change this column only, as many other metadata fields are involved (there are multiple tables which have this field and SQL privileges need to be updated as well). There is a handy tool by Thomas Steinmaurer that can do this automatically, but you'll have to e-mail him directly to get it.
If you're interested in details, you can also check Thomas' paper from one of the Firebird Conferences:
There another, freely available tool called DBUSubst by Vítězslav vejdar. You can get more details and download it from his website:
We also mirror the package here:
As always, please be careful when it. We haven't found any problems, but make sure you have a backup of your database before running the tool.