oracle 分页大于等于小于分页临界点

正确的：

SELECT * FROM (SELECT A.*,ROWNUM RN FROM ( 
select * from t_agent t where  t.agent_parent = 20020 
and t.agent_state = 0 

) A WHERE ROWNUM <= 22) WHERE RN >  0;

错误的：这样只会取出21条数据，到临界点，比如有22条数据，下一页不会显示一条数据，只会看到一页，21条数据，少了一条。

SELECT * FROM (SELECT A.*,ROWNUM RN FROM ( 
select * from t_agent t where  t.agent_parent = 20020 
and t.agent_state = 0 

) A WHERE ROWNUM < 22) WHERE RN >=  0;