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 |
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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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