Have you ever wished you had a self-cleaning AS/400? A query library can become cluttered with physical files and one-time queries if users build database files with Query/400 so they can subsequently query them or join them to other files. Most users cannot delete their own physical files, and it's too much work for you to constantly delete them yourself. Placing these files in QTEMP is not effective because QTEMP is deleted when the job ends.
To solve the problem, build a library called QRYTMP or TMPLIB, and instruct your Query/400 users to build temporary database files there. They can even use the library for one-time queries that they do not want to save. Configure the OS/400 job scheduler to automatically run the CLRLIB command on that new library each night.