To produce an Explain Plan:
explain plan set statement_id = '<SOME_IDENTIFIER>' for /* ------ Your SQL here ------ */
To read an Explain Plan:
select operation, options, object_name from plan_table where statement_id = '<SOME_IDENTIFIER>' start with id = 0 connect by prior id=parent_id and prior statement_id = statement_id;
Q. How can you find an orphan row in a join?
Do a Left Join (= Left Outer Join) and look for nulls.
select * from TABLE_A left outer join TABLE_B on TABLE_A.NAME = TABLE_B.NAME where TABLE_B.ID is null