FAQ
Hi,

I am sorry to have to admit to being the author of a very very silly bug
in unicode handling in DBD::ODBC. The length of UTF16 encoded data was
stored in an unsigned short and this can overflow. An unfortunate side
effect of this bug can be corruption in your perl application. I only
found this issue this morning and no one has reported it to me as yet.
If you are using a unicode enabled DBD::ODBC (the default on Windows)
and use strings larger than 64K I strongly suggest you upgrade. The 1.22
release should appear on CPAN mirrors soon.

If you package DBD::ODBC up (e.g., a PPM for ActiveState) I would be
pleased if you could expedite repackaging version 1.22.

Since 1.21 the changes are:

=head2 Changes in DBD::ODBC 1.22 June 10, 2009

Fixed bug which led to "Use of uninitialized value in subroutine
entry" warnings when writing a NULL into a NVARCHAR with a
unicode-enabled DBD::ODBC. Thanks to Jirka Novak and Pavel Richter who
found, reported and patched a fix.

Fixed serious bug in unicode_helper.c for utf16_len which I'm ashamed to say
was using an unsigned short to return the length. This meant you could
never have UTF16 strings of more than ~64K without risking serious
problems. The DBD::ODBC test code actually got a

*** glibc detected *** /usr/bin/perl: double free or corruption
(out): 0x406dd008 ***

If you use a UNICODE enabled DBD::ODBC (the default on Windows) and
unicode strings larger than 64K you should definitely upgrade now.

=head2 Changes in DBD::ODBC 1.21_1 June 2, 2009

Fixed bug referred to in rt 46597 reported by taioba and identified by
Tim Bunce. In Calls to bind_param for a given statement handle if you
specify a SQL type to bind as, this should be "sticky" for that
parameter. That means if you do:

$sth->bind_param(1, $param, DBI::SQL_LONGVARCHAR)

and follow it up with execute calls that also specify the parameter:

$sth->execute("a param");

then the parameter should stick with the SQL_LONGVARCHAR type and not
revert to the default parameter type. The DBI docs (from 1.609)
make it clear the parameter type is sticky for the duration of the
statement but some DBDs allow the parameter to be rebound with a
different type - DBD::ODBC is one of those drivers.

Martin
--
Martin J. Evans
Easysoft Limited
http://www.easysoft.com

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