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From "Satheesh Bandaram (JIRA)" <derby-...@db.apache.org>
Subject [jira] Created: (DERBY-335) Enhance Derby by adding SYNONYM support. A synonym is an alternate name for a view or a table.
Date Sat, 04 Jun 2005 23:56:40 GMT
Enhance Derby by adding SYNONYM support. A synonym is an alternate name for a view or a table.
----------------------------------------------------------------------------------------------

         Key: DERBY-335
         URL: http://issues.apache.org/jira/browse/DERBY-335
     Project: Derby
        Type: New Feature
  Components: SQL  
    Versions: 10.1.0.0    
 Environment: Generic
    Reporter: Satheesh Bandaram
 Assigned to: Satheesh Bandaram 
     Fix For: 10.1.0.0


Synonym provides an alternate name for a table or a view that is present in the same schema
or another schema. A synonym can also be created for another synonym, causing nesting of synonyms.
A synonym can be used in SELECT, INSERT, UPDATE, DELETE or LOCK TABLE statements instead of
the original qualified table or view name. Note that a synonym can be created for a table
or a view that doesn't yet exists. But the target table/view must be present before the synonym
can be used.

Synonyms are supported by all major database vendors, including Oracle, DB2 and mySQL. DB2
also allows CREATE ALIAS statement, which does exactly same as CREATE SYNONYM. Creating aliases
instead of synonyms is not supported by Oracle or mySQL, so I propose that Derby not support
creating aliases. Synonyms are not part of SQL-2003 spec, but is a common-SQL statement among
major database vendors. SQL standard doesn't pay attention to DDLs as much, so I suspect they
skipped synonyms. 

I will be adding two new DDL statements to Derby:

CREATE SYNONYM <SynonymSchema>.<SynonymName> FOR <TargetSchema>.<TargetName>
DROP SYNONYM <SynonymSchema>.<SynonymName>

Synonyms share the same namespace as tables or views. It is not possible to create a synonym
with same name as a table that already exists in the same schema. Similarly, a table/view
can't be created that matches a synonym already present.


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