RE: [INTERFACES] JDBC next() method - Mailing list pgsql-interfaces

On Wednesday, 14 April 1999 23:18, Peter Mount
[SMTP:petermount@it.maidstone.gov.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.