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RE: [INTERFACES] JDBC next() method

From: Jon Barnett <jbarnett(at)pobox(dot)com>
To: "'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 14:37:03
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-interfaces
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( {} 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");;
nextID = queryResult.getLong(1) + 1;
if (queryResult.wasNull())
	nextID = 0;

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



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