SQL的各種常用演算法問題

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分頁演算法:

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實現分頁，可以使用巢狀查詢，也可以使用儲存過程。不過儲存過程太複雜，執行效率也不一定高，

所以我就用這樣的巢狀語句來實現：

select top 頁大小 * from testtable

where (id >(select max(id) from (select top 頁大小*頁數 id from testtable order by id) as t)) order by id

select * from (select * from scott.emp order by scott.emp.empno) where rownum<=20;

select a.empno from (select * from scott.emp where rownum<=20 order by scott.emp.empno ) a

minus

select b.empno from (select * from scott.emp where rownum<=10 order by scott.emp.empno) b ;

select a.empno from (select * from scott.emp where rownum<=20 order by scott.emp.empno ) a

union all

select b.empno from (select * from scott.emp where rownum<=10 order by scott.emp.empno) b ;

select a.empno from (select * from scott.emp where rownum<=20 order by scott.emp.empno) a

minus

select b.empno from scott.emp b

select a.empno from (select * from scott.emp where rownum<=20 order by scott.emp.empno) a

minus

select b.empno from scott.emp b where rownum<=10 ;

select a.empno from (select * from scott.emp where rownum<=20 order by scott.emp.empno) a

intersect

select b.empno from (select * from scott.emp where rownum<=10 order by scott.emp.empno) b ;

select aa.empno from ( select * from (select * from scott.emp order by scott.emp.empno) a where rownum<=20 ) aa

minus

select bb.empno from ( select * from (select * from scott.emp order by scott.emp.empno) a where rownum<=10 ) bb

select a.empno from (select scott.emp.empno from scott.emp where rownum<=20 order by scott.emp.empno) a

minus

select b.empno from (select scott.emp.empno from scott.emp where rownum<=10 order by scott.emp.empno) b;