第 8 题 (多选题)： Which two are benefits of external tables.

A. They support UPDATES which transparently updates records in the file system as if they were table. B. They can be queried while the database is in the MOUNT state like dynamic performance views . C. They support DELETEs which transparently deletes records in the file system as if they were table rows. D. The results of a complex join or aggregating function or both can be unloaded to a file for transportation to another database. E. They can be queried, transformed, and joined with other tables without having to load the data first 显示答案