OracleÖÐrownumµÄÓ÷¨

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select sal from emp where rownum=1; //²éѯµÃµ½µÚÒ»ÐмǼ
select sal from emp where rownum=5; //²»¿ÉÒÔ²éѯµ½µÚÎåÐмǼ£¬ÒòΪrownum ×ÜÊÇ´Ó1¿ªÊ¼²éѯµÄ£¬¹ÊÕâÖÖ·½Ê½²»¿ÉÒÔÖ±½ÓµÃµ½µÚ¼¸ÐеļǼ¡£ÈôÏëµÃµ½µÚÎåÐмǼ£¬Ó¦²ÉÓÃÈçÏ·½Ê½£º
select r,sal from (select rownum r,sal from emp) where r= 5;
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  select rownum,sal from emp where rownum<5;
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          select r,sal from (select rownum r,sal from emp ) where r>5;
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  select r,sal from (select rownum r,sal from emp) where r>=3 and r<=8;
5¡¢rownum ÓëÅÅÐò
       select rownum,sal from emp order by sal;
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select rownum,sal from (select * from emp order by sal) ;
select rownum, sal from (select * from emp order by sal ) where rownum <5;
select r, sal from (select rownum r,sal from (select * from emp order by sal )) where r >5;
select r, sal from (select rownum r,sal from (select * from emp order by sal ))
where r >5 and r < 10;