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OracleÖÐΪʲôwhere rownum > 3 ²éÕÒ²»µ½Êý¾Ý£¿

²éѯ±íempÖÐËùÓÐÊý¾Ý
select emp_id,rownum from emp
µÚÒ»²½£¬²éѯ½á¹û,rownum´ý¶¨
emp_id rownum
1         ?   1
2         ?   2
3         ?   3
4         ?
µÚ¶þ²½£¬ÏÖÔÚ¼ÙÉèÓÃrownum < 3µÄÌõ¼þÀ´¹ýÂË
µÚÒ»ÐУ¬rownum³õʼ·ÖÅäΪ1£¬Âú×ãrownum <3µÄÌõ¼þ£¬È»ºórownum¼Ó1
µÚ¶þÐУ¬rownumÏÖÔÚΪ2,Âú×ã < 3µÄÌõ¼þ,È»ºórownum¼Ó1
.....
µÚ¶þ²½£¬ÏÖÔÚ¼ÙÉèÓà rownum > 2µÄÌõ¼þÀ´¹ýÂË
ÏÖÔÚ¿´µÚÒ»ÐУ¬rownum³õʼ·ÖÅäΪ1£¬ ²»Âú×ãrownum>2µÄÌõ¼þ,rownum²»»á¼Ó1
µÚ¶þÐУ¬rownum»¹ÊÇ1£¬Í¬Ñù²»Âú×ã>2µÄÌõ¼þ
....
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    select * from
               (select t.*,rwonum rn
              from emp t
               where rownum < 5 )
       where rn > 3


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1. Read the Data Block.
2. Read the Row Header.
3. Check the Lock Byte to determine whether there's an ITL entry.
4. Read the ITL entry to determine the Transaction ID (Xid).
5. Read the Transaction Table using the Transaction ID. If the transaction has been committed and has a System Commit ......

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OracleÊý¾Ý¿â»¹Õæ²»ºÃÕû

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ORACLE RAC¹¤×÷Ô­Àí


ORACLE RAC¹¤×÷Ô­Àí
ORACLE RAC¹¤×÷Ô­Àí
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