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From: Patrick Roemer <sangamon@netcologne.de>
Newsgroups: comp.lang.java.programmer
Subject: Re: Which databases are the most used with Java
Date: Tue, 15 Aug 2017 16:14:52 +0200
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Responding to Cecil Westerhof:
> Patrick Roemer <sangamon@netcologne.de> writes:
> 
>> Responding to Cecil Westerhof:
>>> Earlier I was told that the way to do things was something like:
>>>     try (Statement stmtOldest = conn.createStatement();
>>>          ResultSet rsOldest   = stmtOldest.executeQuery(OLDEST_USED)
>>>          Statement stmtNewest = conn.createStatement();
>>>          ResultSet rsNewest   = stmtNewest.executeQuery(OLDEST_USED)
>>>          Statement stmtCount  = conn.createStatement();
>>>          ResultSet rsCount    = stmtCount.executeQuery(OLDEST_USED)) {
>>
>> Sure about that? I haven't seen any such suggestion in recent threads.
>> To the contrary, more than once you have been advised to reuse one
>> statement to create multiple result sets in sequence.
> 
> Yes I am sure about that. But probably another thread.

I am sure I haven't seen it *in recent threads*. I'd love to see a
pointer to that post.

>> You seem to insist on Statement being an evil ploy designed by the JDBC
>> inventors to force you to write unnecessary boiler plate code when all
>> you want is just a ResultSet. Whatever follows from this line of
>> reasoning is not likely to be correct or useful, I'm afraid.
> 
> I do not see Statement as an evil ploy. But I think that with try with
> resources it is something you do not need explicit anymore.

This just doesn't make sense. try-with-resources is just syntactic
sugar for a try-catch-finally pattern, the semantics are unaffected.

In situations where you really only want a one-shot ResultSet, something
like your custom helper #executeQuery() method /may/ make sense. But
that would be just as useful or useless as with the "classic"
try-catch-finally pattern.

In almost all other cases, e.g. when sequencing a number of ResultSets,
one should go for reuse of a single, explicit Statement. If only because
bluntly creating one statement per ResultSet may be harmful for
performance - one cannot know how costly creation and teardown of a
Statement is going to be. And again, try-with-resources or try-catch
finally doesn't have any impact on this consideration.

Best regards,
Patrick