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;