SQL for DBA's is a collection of the essential SQL-statements needed for monitoring a database. They are not my most recent scripts; but most of them have been used and tested for years and proven their worth.  

Usage hints

• All scripts should be run as user SYSTEM in Sqlplus.
• Compatible: Oracle 9, Oracle 10 and upwards.
• Most statements can be copy / pasted straight into Sqlplus
• However the stmts containing variables (&variablename) have to be run as a ".sql" file from Sqlplus:

    SQL> "start filename.sql" or 
    SQL> "@filename.sql" or
    SQL> "@filename"  

Included are statements useful for storage, free space and extents and the database users and their activity. Also an overview of database objects by owner, Create database statements and Plan table statements.