[jira] Commented: (DERBY-147) ERROR 42X79 not consistant ? - same column name specified twice

     [ 
http://issues.apache.org/jira/browse/DERBY-147?page=comments#action_59875 ]
     
Bernd Ruehlicke commented on DERBY-147:
---------------------------------------

Ok I made the changes and build Derby - and tested it - seams to work.

We may consider to make this change permanent. 

Any reason for this error log was added ?

Here the code snipled (need to chnage getOrderBy(String, String) and 
getOrderBy(String, String, int)

...
                        if (columnName.equals( resultColumn.getName()) )
                        {
                                if (retVal == null)
                                {
                                        retVal = resultColumn;
                                }
//      DERBY-147                               else if (index < size - 
orderBySelect)
//      DERBY-147                               {
//      DERBY-147                                       throw 
StandardException.newException(SQLState.LANG_DUPLICATE_COLUMN_FOR_ORDER_BY, 
columnName);
//      DERBY-147                               }
                                else
                                {// remove the column due to pullup of orderby 
item
                                        removeElement(resultColumn);
                                        decOrderBySelect();
                                        break;
                                }
                        }
...


By the way - if already at the code - and since the code is more or less the 
same  would be handy to refactor the getOrderBy(String, String) to 

getOrderBy(String, String)
{
   return getOrderBy(String, String, null);
}

and handle "null" in the String, String, int method.


B-)

> ERROR 42X79 not consistant ? - same column name specified twice
> ---------------------------------------------------------------
>
>          Key: DERBY-147
>          URL: http://issues.apache.org/jira/browse/DERBY-147
>      Project: Derby
>         Type: Bug
>     Reporter: Bernd Ruehlicke

>
> 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.

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