http://www.oracle.com/webfolder/technetwork/cn/tutorials/obe/db/10g/r2/2day_dba/index.htmlhtml
https://docs.oracle.com/cd/B19306_01/server.102/b14196/toc.htmweb
https://docs.oracle.com/cd/E11882_01/index.htmoracle
https://docs.oracle.com/database/122/index.htmlserver