System Tables 
The database system contains a series of system tables with information about database objects and their connection to each other, statistics system tables, monitor system tables and loader system tables.
The following information describes how to evaluate the system tables.
When you specify SELECT statements for the system tables, you have to bear in mind some general information
To find out which system table contains information for a particular database term, consult the list of database terms.
To find out which information a particular system table can provide, see the examples of SELECT statements in the section on evaluating system tables. The examples make use of the demo data for the SQL Tutorial.
For a complete definition of some of the most important system tables, see Definition of the System Tables.