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Conference ulysse::rdb_vms_competition

Title:DEC Rdb against the World
Moderator:HERON::GODFRIND
Created:Fri Jun 12 1987
Last Modified:Thu Feb 23 1995
Last Successful Update:Fri Jun 06 1997
Number of topics:1348
Total number of notes:5438

410.0. "Oracle to SQL translation" by ODIHAM::CHANDARANA () Wed Aug 23 1989 13:24

    
    
    Hi
    
    	A customer of ours is trying to convert from Oracle to RDB-SQL
    and wished to know how to translate the following relational 
    operators to our SQL
    
       MINUS,UNION,CROSS,OUTER JOIN,INTERSACT,NON-EQUIJOIN.
    
       Thanking you in Advance 
    
    Roy	
       
 
    
    
    
    
    
    
    
T.RTitleUserPersonal
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410.1Some thoughts.COOKIE::MELTONStandards and serendipity--the ideal combinationMon Aug 28 1989 17:1134
Roy,

I am not an expert on Oracle and its particular (peculiar?) variant of
SQL, so my remarks may not be as helpful as others' might be.  However,
I'll give you what I have available.

Note 11.11 in the DSRI conference (COOOKIE::DSRI) analyzes DSRI against
Codd's 12 rules.  At the end of that note, there is an analysis of how, in
DSRI, to simulate those operations that are not specifically provided
(e.g., outer join).  That may be of a *little* use to you.

I do not believe that VAX SQL currently implements the MINUS (the next 
SQL standard will call it "DIFFERENCE") operator.  

I believe that VAX SQL currently implements UNION.  

In standard SQL, a join of any sort, including a cross product (CROSS), is
indicated simply by listing multiple tables in the FROM clause--the
keyword CROSS is not required and is at most a noise word (unless Oracle
has some clever new definition for the word or syntax for the feature).

OUTER JOIN is not yet, I believe, implemented in VAX SQL.  However, it can
be simulated (DSRI 11.11) using UNIONs.

I do not believe that VAX SQL currently implements INTERSECT.  

I can't imagine why Oracle would have a specific keyword for NON-EQUIJOIN,
but you can rest assured that VAX SQL can easily accomplish them by simply
using an operator other than "=" in the WHERE clause predicates.

Perhaps a VAX SQL maven can fill in the holes that I left.

Good luck,
   Jim
410.2Ask in the BANZAI::SQL conference!COOKIE::BERENSONVAX Rdb/VMS VeteranTue Aug 29 1989 16:582
UNION is not currently supported in VAX SQL, unless of course you are a
field test site :-)