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From "Greg Monroe" <Greg.Mon...@DukeCE.com>
Subject RE: Database independent error trapping.
Date Fri, 09 Feb 2007 14:34:06 GMT
Three or four years ago, I did some coding on a 
pre-Torque system that tried to deal with this issue.  
One major problem I remember is that there is no true 
standard for SQL error codes.  And what standards there 
are don't seem to be implimented very well (or at all).

To add to the confusion, the error codes are actually
generated/interpreted by the JDBC layer and not the
DB vendor.  So, you can't just say "MS SQL does it this
way", you have to say MS's JDBC driver does it this way, 
Avinar's does it this way, jTDS does it this way, etc.
I even found some variance in returne codes between driver
versions by the same vendor.

That said, what I ended up doing in my pre-Torque code
was to write a bit of "JDBC driver profiler" code that 
ran when the system started up.  This created the set
of errors my app was concerned with, stored them away,
and them my error checking code compared to these.

I'm not sure this can be applied to Torque since to find
the errors, your DB connect account rights have to be able 
to do thingslike create / delete tables, etc. that some
security folks frown on.

Hmm, I wonder if a new Torque 4 ToDo would be a bit of 
code that wraps any Torque exception with a check against
an optional application specific SQL RC to Exception type 
mapping. We could supply a "driver mapping" utility to 
generate this mapping file for the most common errors.

Just remember as I said at the start, this is from a 
few years back.  The state of things may have changed.
(but I know a lot of folks still using old drivers too...)

Greg

> -----Original Message-----
> From: Christopher Thill [mailto:cthill69@yahoo.com] 
> Sent: Friday, February 09, 2007 6:47 AM
> To: Apache Torque Users List
> Subject: Database independent error trapping.
> 
> I am wondering if there is a way to do database independent 
> error trapping.
> 
> For example on a table/object that has a unique key I just 
> invoke the .save() method and and trap any exception.  I look 
> at the exception to see if it was a duplicate value in the 
> unique column that caused the error and then explain this to 
> the user in a friendly message.
> 
> My problem is that I want the system to portable to different 
> database so I do not want to do something
> like:
> 
>     eSql = (SQLException) t;
>     if ( !eSql.getSQLState().equals("23505") ) 
> 
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