Message-Id: <24715.322386@fatcity.com> From: "Darrell Landrum" Date: Wed, 19 Mar 2003 09:58:21 -0600 Subject: Re: Re: Rownum That's correct, there's no rownum of 0. ex. SQL> select rownum, username from dba_users; ROWNUM USERNAME ---------- ------------------------------ 1 SYS 2 SYSTEM 3 OUTLN 4 OEM_DLAND 5 DBSNMP 6 HR 7 PM 8 DLANDRUM 9 OE 10 WMSYS 11 ORDSYS 12 ORDPLUGINS 13 MDSYS 14 CTXSYS 15 QS_CS 16 QS_CB 17 QS_CBADM 18 QS_OS 19 QS_ES 20 QS_WS 21 QS 22 QS_ADM 23 SH 24 XDB 25 ANONYMOUS 26 WKSYS 27 WKPROXY 28 ODM 29 ODM_MTR 30 OLAPSYS 30 rows selected. I'm not sure what you mean by 'judge the select return', but the only real use I can think of for rownum is to restrict your query to a small random sampling of your data... ex. SQL> select table_name, tablespace_name from dba_tables 2 where rownum < 5; TABLE_NAME TABLESPACE_NAME ------------------------------ ------------------------------ SEG$ SYSTEM CLU$ SYSTEM OBJ$ SYSTEM FILE$ SYSTEM >>> liujd@cti.ac.cn 03/19/03 08:33AM >>> Darrell Landrum,-? +ْي thanx for your explaination. I wonder :whether i can judge the select return. I find the rowNUM is not 0, is right? ======= 2003-03-19 05:03:00 -?+++ -++-- +ْ ======= >Santosh, > >Good question. Actually these 2 are not related. >Rowid is an actual attribute assigned to each row of a table and is unique. >Rownum is logically assigned to rows returned in a query (nothing to do with the table). It is assigned sequentially as rows are returned (meaning if you can't have a rownum 2 until you've gotten a rownum 1). > >Ex. >SQL> select rowid from dual; > >ROWID >------------------ >AAAACsAABAAAAGkAAA > >SQL> select rownum from dual; > > ROWNUM >---------- > 1 > >SQL> select rownum from dual where rownum=2; > >no rows selected > >SQL> select rownum from dual where rownum < 2; > > ROWNUM >---------- > 1 > > >Hope this was helpful, >Darrell > > > > >>>> vsantosh@psi.soft.net 03/19/03 03:43AM >>> >Hello list, > > I wanted to know the concept of Rownum.. Is it similar to Row Id ? > >Thanks and Regards, >Santosh > > >---------------------------------------------------------------------------- >---- > > >-- >Please see the official ORACLE-L FAQ: http://www.orafaq.net >-- >Author: Darrell Landrum > INET: dlandrum@zalecorp.com > >Fat City Network Services -- 858-538-5051 http://www.fatcity.com >San Diego, California -- Mailing list and web hosting services >--------------------------------------------------------------------- >To REMOVE yourself from this mailing list, send an E-Mail message >to: ListGuru@fatcity.com (note EXACT spelling of 'ListGuru') and in >the message BODY, include a line containing: UNSUB ORACLE-L >(or the name of mailing list you want to be removed from). You may >also send the HELP command for other information (like subscribing). = = = = = = = = = = = = = = = = = = = = يييييييييييييييي+- +±ْي يييييييييييييييي-)+ ½ ييييييييييييييييliujd@cti.ac.cn يييييييييييييييييييي2003-03-19 -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: =?GB2312?Q?=C1=F5=BC=CC=B6=AB?= INET: liujd@cti.ac.cn Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru@fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L