Subject Re: [IBO] strange intermitent Access Violation errors likely due to a conversion issue?
Author Jason Wharton
> I've brought this over from the Firebird group.
> Helen's last response is below.
> I trust the "Migration and Installation Guide" is for Firebird that I
> should refer too? I did look at what I think is the release notes of IBO
> 4.8.7 and....I think i've got a couple issues.
> here's a couple questions:
> would any of the below cause the error to not be showing up every time?
> most troubling to me is that I cannot ever duplicate the Access Violation
> errors the customers see on my own PC with their database. Even when I
> Citrix in to their system, i cannot duplicate the errors. and? they
> don't happen every time to the customer either (exact same keystrokes by
> them do not generate the problem everytime even though it's the exact same
> SQL and, obviously, code in my application).
> 1) in my BDE application, I used wwQuery. I did NOT install and use
> IPIBODataset.pas to get and use wwIBOQuery. instead, I use IBOQuery's.
> should i switch them all to wwIBOQuery? would that matter for the SQL
> itself (ie. it doesn't make it to the grid before it AVs out)

This is not a problem unless you are using controls that require the
additional functionality that the TwwXX based components provide.

> 2) i do a lot of
> select p.*, l.* from MdPartL P, LinksMP L
> where P.uniqueKey = L.partUniqueKey
> and
> L.ModelUniqueKey = :UniqueKey
> it reads like that is a total no-no with FB2.1 and IBO 4.8.7. Would that
> not being a proper "join" syntax, would that cause an AV Error everytime
> or just once in a while?

It wouldn't cause AVs.

IBO wouldn't give correct treatment to your JOIN condition if you leave it
in the WHERE clause. If you want to have the join criteria remain in a WHERE
clause then you need to use the JoinLinks property. This way IBO will add it
to your WHERE clause at the time the query is prepared.

> 3) i do have persistent fields in persistent queries in my
> datamodule...sounds like for the few queries that are in the functions
> that are AV erroring, I should delete the fields and re-add them. I will
> do this.

This should help.

> 4) the KeyLink property...i don't explicity set it. would that cause AV
> errors all the time or could it be just once in a while for the exact same
> SQL? i should set those too....

This won't cause AVs.

> i use Firebird-
> I will explore more and look forward to any suggestions!
> TIA!
> kelly

Jason Wharton