How to find invalid objects and syntax to compile?

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select 'alter ' || OBJECT_TYPE || ' '  ||OWNER|| '.' ||object_name||   ' COMPILE;'   FROM dba_objects where OBJECT_TYPE != 'PACKAGE BODY' and status='INVALID' order by OBJECT_TYPE;

select 'alter PACKAGE '  ||OWNER|| '.' ||object_name||   ' COMPILE BODY;'   FROM dba_objects where OBJECT_TYPE = 'PACKAGE BODY' and status='INVALID';