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Date: Sat, 5 Aug 2006 09:14:17 -0700 (PDT)
From: Thomas Fischer <tfischer@apache.org>
To: ddlutils-dev@db.apache.org
Subject: Customisation of jdbc->sql type mapping
Message-ID: <20060805083452.H90790@minotaur.apache.org>
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Is there any support planned for customisation the mapping from jdbc types 
to sql types ? For example, users might want to use nvarchar2 instead of 
varchar for some reason.

In torque, users could do this using the db.props file for the different 
databases up to Torque 3.1.1. In Torque 3.2, the db.props file is gone and 
it is quite difficult for users to define their own mappings. This needs 
to be changed in Torque. However, it would make sense to do this in a 
manner that ddlutils might support in the future.

My current plan for Torque is to use the "domain" attribute in the torque 
schema file. A domain (I'm not finding this name intuitive, maybe there's 
a better one) is a kind of "custom column type" the user can define. For 
example, the user can define a type "SHORTVARCHAR" which corresponds to a 
varchar column with size 20. The user then can use the type "shortvarchar" 
as column type in the schema, and does not need to specify the size of 20 
everywhere.

The plan would be to give the domain an additional attribute "sqlType" 
where also the sql type can be changed. So to use NVARCHAR columns, the 
user would be creating a domain called NVARCHAR2, and set its type to 
VARCHAR (i.e. it behaves like a varchar column for the java part) and its 
sqlType to NVARCHAR2.

As far as I know, ddlutils does not support the domain stuff at the 
moment, but there is a request in jira (ddlutils-84) that it should do so. 
Do you plan to implement something of the sort, or would you think that 
another way of dealing with custom mappings is more appropriate ?

      Thomas