How to analyze all tables with theirs indices where statistics is equal to null.

For preparing a script for analyzing all tables with its indices where statistics is equal to null you can use this query:

select 'exec dbms_stats.gather_table_stats( ownname=>''' ||owner||''',tabname=>'''|| table_name||''', estimate_percent=>20,cascade=>true);' comm from dba_tables where last_analyzed is null and owner not in ('SYS','SYSTEM');