Error while updating SQL Statement in OAF View Object Extension

Hello Every One ,

I am trying to extend a VO while adding a column to the SQL statement facing the below error

Illegal name . It is either a reserved word or object of given name already exists.

Due to this the new column is not appearing in Attribute mapping section.

Based on my check i found the error is happening due to constant values in select statement .

There are 5 constant value like below

Select 'ChgQtyType',

     'ChgPriceType',

     'ChgPrmDateType',

      'ChgAmntType',

      'ShipStatusType',

      'DispStatus',

FROM ....

when commented above values in select statement the error is not appearing and the new column is shown in attribute mapping window