ORACLE几种分页查询SQL语句
ORACLE几种分页查询SQL语句
一、效率高的写法
1.无ORDER BY排序的写法。(效率最高)
(经过测试，此方法成本最低，只嵌套一层，速度最快！即使查询的数据量再大，也几乎不受影响，速度依然！)
SELECT *
FROM (SELECT ROWNUM AS rowno, t.*
FROM emp t WHERE hire_date BETWEEN TO_DATE ('20060501', 'yyyymmdd') AND TO_DATE ('20060731', 'yyyymmdd') AND ROWNUM <= 20) table_alias WHERE table_alias.rowno >= 10;
2.有ORDER BY排序的写法。(效率较高)
(经过测试，此方法随着查询范围的扩大，速度也会越来越慢)
SELECT *
FROM (SELECT tt.*, ROWNUM AS rowno FROM ( SELECT t.*
FROM emp t WHERE hire_date BETWEEN TO_DATE ('20060501', 'yyyymmdd') AND TO_DATE ('20060731', 'yyyymmdd') ORDER BY create_time DESC, emp_no) tt WHERE ROWNUM <= 20) table_alias WHERE table_alias.rowno >= 10;
二、效率垃圾但又似乎很常用的分页写法
SELECT *
FROM (SELECT ROWNUM AS rowno, t.*
FROM k_task t WHERE flight_date BETWEEN TO_DATE ('20060501', 'yyyymmdd') AND TO_DATE ('20060731', 'yyyymmdd')) table_alias WHERE table_alias.rowno <= 20 AND table_alias.rowno >= 10;--TABLE_ALIAS.ROWNO between 10 and 100;