Oracle paging Query

-- MySql, paging

-- Select * from biaoming where tiaojian limit num1 (start), num2 (size)

-------- Oracle paging, keyword rownum

----

Select ename, rownum from emp;

Select ename, rownum from (select * from emp );

---- Layer-3 filtering, High Efficiency

Select t2. * from (select t1. *, rownum rn from (select * from emp) t1 where rownum <= 6) t2 where rn> = 4;

-- Layer 1:

-- Select * from emp ..

-- Layer 2:

-- Select * from (first layer) where rownum <= 6 (endNum );

-- Layer 3:

-- Select * from (second layer) where rownum> = 4 (startNum );

-- Query from 7th to 10th people according to the order of employment time

Select t2. * from (select t1. *, rownum rn from (select * from emp order by hiredate) t1 where rownum <= 10) t2 where rn> = 7;

--------------- Merge Query

------ Union

------ Union all

------ Intersect