Oracle paging

Detailed explanation of several paging query statements of Oracle: http://database.51cto.com/art/200904/118737.htm
ORACLE paging solution under large data volume: http://ddkangfu.blog.51cto.com/311989/ 1425797/
oracle paging data duplicate data is incorrect: https://my.oschina.net/u/852445/blog/402325
Example:

SELECT *
			FROM
			(
			SELECT RS.AMOUNT,RS.AREA,RS.AREANAME,[color=red]ROWNUM rn
			FROM
			(
			SELECT (
			CASE
			WHEN oy.AMOUNT IS NULL THEN
			    ny.AMOUNT-0
			WHEN ny.AMOUNT IS NULL THEN
			    0-oy.AMOUNT
			ELSE
			   ny.AMOUNT-oy.AMOUNT
			END) AS amount,NY.AREA,NY.areaName
			FROM
			(SELECT "SUM"(VI.AMOUNT) AS AMOUNT ,VI.AREA, dm.AREA_NAME as areaName FROM VI_INCOME_ITEM_MAPPING VI
			LEFT JOIN DM_AREA dm ON VI.AREA = dm.AREA_CODE
			WHERE VI.T_ITEM =  #{BudgetTItem,jdbcType=VARCHAR} AND VI.BLEVEL ='3'
			AND "SUBSTR"(VI.TXN_DATE,1,6) <![CDATA[ >= ]]>  #{startMonth,jdbcType=VARCHAR}
		    AND "SUBSTR"(VI.TXN_DATE,1,6)  <![CDATA[ <= ]]>  #{endMonth,jdbcType=VARCHAR}
			GROUP BY VI.AREA,dm.AREA_NAME) ny
			LEFT JOIN
			(SELECT "SUM"(VI.AMOUNT) AS AMOUNT ,VI.AREA, dm.AREA_NAME as areaName FROM VI_INCOME_ITEM_MAPPING VI
			LEFT JOIN DM_AREA dm ON VI.AREA = dm.AREA_CODE
			WHERE VI.T_ITEM = #{BudgetTItem,jdbcType=VARCHAR} AND VI.BLEVEL ='3'
			AND "SUBSTR"(VI.TXN_DATE,1,6) <![CDATA[ >= ]]> #{lastStartMonth,jdbcType=VARCHAR}
			AND "SUBSTR"(VI.TXN_DATE,1,6)  <![CDATA[ <= ]]> #{lastEndMonth,jdbcType=VARCHAR}
			GROUP BY VI.AREA,dm.AREA_NAME) oy
			ON NY.AREA = OY.AREA
			ORDER BY amount DESC ) [color=red]rs WHERE ROWNUM <= 10) WHERE rn >0

Note that ROWNUM is used for the inner layer of the red font, and RN is used for the outer layer. Generally, when Oracle selects for the first time, there is ROWNUM, which can be used for paging in the second layer. There are two methods for

paging :
the first one:

SELECT * FROM (SELECT t.*,ROWNUM as rowno FROM (SELECT * FROM test ORDER BY ADD_TIME ) t )
 WHERE rowno  BETWEEN 200001 AND 300000;

The second:

SELECT * FROM ( SELECT t.*,ROWNUM as rowno FROM (SELECT * FROM test ORDER BY ADD_TIME) t WHERE ROWNUM  <= 300000)
WHERE rowno >=200001

The second is more effective than the first, because the second locks the paging result set, while the first is to paginate from all the records in the table;
for two-level nested paging queries such as:
Example:

select （select * from test ORDER BY ADD_TIME） where ROWNUM between 100000 and 200000

For ORDER BY ADD_TIME, the order field ADD_TIME field must be a unique index, otherwise the
result set is empty, or the data is duplicated.