[ http://issues.apache.org/jira/browse/DERBY-147?page=comments#action_12422749 ] Satheesh Bandaram commented on DERBY-147: -----------------------------------------
Last time this patch was reviewed, there was also another concern about truely ambigious columns, like: Select a+b as x, c+d as x from T order by x This query should probably raise an error as X in ORDER BY clause is truely ambigious. To make this work, resolution process needs to find out if two different references to X actually correspond to same expression (or column) so that following is allowed: select a as x, a as x from T order by x select a, a from T order by a > ERROR 42X79 not consistant ? - same column name specified twice > --------------------------------------------------------------- > > Key: DERBY-147 > URL: http://issues.apache.org/jira/browse/DERBY-147 > Project: Derby > Issue Type: Bug > Components: SQL > Reporter: Bernd Ruehlicke > Attachments: derby-147-10.0.2.1.diff, derby-147.diff > > > This happens from JDBC or ij. Here the output form ij> > ij version 10.0 > CONNECTION0* - jdbc:derby:phsDB > * = current connection > ij> select a1.XXX_foreign, a1.native, a1.kind, a1.XXX_foreign FROM > slg_name_lookup a1 ORDER BY a1.XXX_foreign; > ERROR 42X79: Column name 'XXX_FOREIGN' appears more than once in the result > of the query expression. > But when removing the ORDER BY and keeping the 2 same column names it works > ij> select a1.XXX_foreign, a1.native, a1.kind, a1.XXX_foreign FROM > slg_name_lookup a1; > XXX_FOREIGN > |NATIVE > |KIND |XXX_FOREIGN > > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- > > 0 rows selected > ij> > So - it seams to be OK to specify the same column twice - as long as you do > not add the ORDER BY clause. > I woul dof course like that the system allows this - but at leats it should > be consistant and either allow both or none of the two queries above. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
