FreeTDS Development Group

[Bob Kline <bkline AT rksystems.com>]

Henry:

Thanks for your reply.  However, I'm a bit confused.  First, I wasn't
the one posting the original problem, so I assume you just got me mixed
up with Jon, who was.

Also, I may be exposing some gross misunderstanding of a basic JDBC
concept, but I'm not sure what cursors have to do with the setObject()
method.  I had thought that setObject() was simply a thin layer
providing a simple convenience of mapping arbitrary objects to JDBC
types.  Help me understand how this fits in with cursor programming.

Cheers,
Bob

On Tue, 12 Sep 2000, Henry Lafleur wrote:

> The way that freetds_jdbc is designed, it seems that it JDBC 1.0 was
> in mind. The process seems to be:
> 
> 1) Take the user's (the user being a Java program) query and send it to the
> SQL server.
> 2) Take the response from the SQL server and read it as the user goes
> through the result set using next(), if there is a result set. Let the user
> go to other result sets, if any.
> 
> (My description is a little oversimplified here.)
> 
> Given this, how would the setObject be implemented in freetds_jdbc? It seems
> that the only way to do this would be for freetds_jdbc to work differently.
> One way would be to open a cursor and keep the connection open as the user
> moves around the result set with next(), prev(), first(), last(),
> movetoinsertrow(), etc. (I didn't verify the method names here) and to
> compute update statements using the "where current of <cursor>" SQL
> condition. The insert statement is straightforward: use Insert <table name>
> ... In other words, implement JDBC 2.0.
> 
> I know that the 1.0 implementation is the current goal, but has anyone
> discussed this?
> 
> For your problem Bob, I use an abstraction layer on top of JDBC to handle
> table navigation and saving data back to the database. My abstraction layer
> requires that tables have keys. Without keys how do you know which record in
> the table to change? (a semi-rhetorical question) Since you can't use
> cursors, there is no way to know that the record that you are looking at is
> the only record that will be changed in an update statement unless you have
> a table-wide unique identifier. 
> 
> An MS-SQL timestamp field will also work as a key. This also has the
> advantage that if the record has changed since you read it, your update will
> not change it again since timestamps change on update. You would need to
> check to see if no records were affected by the update and tell the user
> that someone else changed the record while you were looking at it.
> 
> Stored procedures are another solution, which brings us to server-side
> programming. They are also much faster that other solutions.
> 
> Henry
> 
> 
> > -----Original Message-----
> > From: Strande, Jon [mailto:JohnS AT nwpasta.com]
> > Sent: Tuesday, September 12, 2000 12:53 PM
> > To: TDS Development Group
> > Subject: [freetds] Re: [JDBC] setObject() - not implemented
> > 
> > 
> > Bob,
> > 
> > Sorry about that, I meant to write that it 
> > does not say that it does not work. Quite a
> > difference... My Readme says: "The prepared
> > statement class does not have all the data 
> > types implemented yet". Again, my apologies.
> > 
> > So, I am out of luck huh? 
> > 
> > Thanks Bob,
> > 
> > Jon
> > 
> > -----Original Message-----
> > From: Bob Kline [mailto:bkline AT rksystems.com]
> > Sent: Tuesday, September 12, 2000 1:58 PM
> > To: TDS Development Group
> > Subject: [freetds] Re: [JDBC] setObject() - not implemented
> > 
> > 
> > On Tue, 12 Sep 2000, Strande, Jon wrote:
> > 
> > > I have searched for answer for this, so I apologize if this 
> > is a repeated
> > > question. 
> > > 
> > > NT 4.0 Sp 5
> > > IIS 4
> > > Tomcat 
> > > JDK 1.3
> > > freetds - JDBC V 1.3 1999/03/09 17:15:49
> > > 
> > > In the readme file it says that setObject works
> > > yet I am getting an error "not implemented" when
> > > I call:
> > > java.lang.Integer myInteger = new... etc.
> > > myPreparedStatement.setObject(i, myInteger);
> > > 
> > 
> > The README file that I have doesn't say what yours does.  The 
> > one I have
> > says that getObject() is implemented for all SQLServer datatypes, but
> > says nothing whatsoever about setObject() (which is indeed not
> > implemented).  Where did you get your copy of the README file?
> > 
> > -- 
> > Bob Kline
> > mailto:bkline AT rksystems.com
> > http://www.rksystems.com
> > 
> > 
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-- 
Bob Kline
mailto:bkline AT rksystems.com
http://www.rksystems.com