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RE: [INTERFACES] JDBC next() method

From: Peter Mount <petermount(at)it(dot)maidstone(dot)gov(dot)uk>
To: jbarnett(at)pobox(dot)com, "'Peter Mount'" <petermount(at)it(dot)maidstone(dot)gov(dot)uk>, "'pgsql-interfaces(at)hub(dot)org'" <pgsql-interfaces(at)hub(dot)org>
Subject: RE: [INTERFACES] JDBC next() method
Date: 1999-04-14 14:51:39
Message-ID: A9DCBD548069D211924000C00D001C441D9BDF@exchange.maidstone.gov.uk (view raw or flat)
Thread:
Lists: pgsql-interfaces
That's correct (we use that syntax in the driver's source ourselves).

wasNull() is only valid after a getxxx() call, but only for the last
call.

Peter

--
Peter T Mount, IT Section
petermount(at)it(dot)maidstone(dot)gov(dot)uk
Anything I write here are my own views, and cannot be taken as the
official words of Maidstone Borough Council

-----Original Message-----
From: Jon Barnett [mailto:jbarnett(at)pobox(dot)com]
Sent: Wednesday, April 14, 1999 3:37 PM
To: 'Peter Mount'; 'pgsql-interfaces(at)hub(dot)org'
Subject: RE: [INTERFACES] JDBC next() method


On Wednesday, 14 April 1999 23:18, Peter Mount 
[SMTP:petermount(at)it(dot)maidstone(dot)gov(dot)uk] wrote:
> This looks ok.
>
> queryResult is null if there was an error in the query, so you should
> check for that.
>
> However, normal use would have the result parsed within a
> while(queryResult.next()) {} loop, so your interpretation is correct.

I don't think the query should give an error - as the query is at least 
syntactically correct.  Certainly, if I check for a queryResult == null,
the 
condition doesn't occur for an empty table.

I just had a quick browse on some old JDBC notes and it looks like the
correct 
solution is:

queryResult = dbStatement.executeQuery("select max(history_id) from
history");
queryResult.next();
nextID = queryResult.getLong(1) + 1;
if (queryResult.wasNull())
	nextID = 0;

Note:  queryResult.wasNull() only works immediately after calling a
getxxx 
method.

Thanks.

JonB.

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Next:From: Loic Mahe'Date: 1999-04-14 15:52:24
Subject: Pb. when compiling jdbc (postgresql-6.4.2)
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Subject: RE: [INTERFACES] JDBC next() method

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