Bug confirmed on Linux i386, perl v5.8.5, SQL::Statement 1.15. The patch seems to resolve the issue:

$ uname -a
Linux linux 2.6.9-55.0.12.EL #1 Fri Nov 2 10:57:39 EDT 2007 i686 i686 
+i386 GNU/Linux

$ grep ^\$VERSION /usr/lib/perl5/site_perl/5.8.5/SQL/Statement.pm
$VERSION = '1.15';

# 669178.pl is identical to source from parent node
$ perl 669178.pl
DBD::CSV::db do failed: Can't use an undefined value as an ARRAY refer
+ence at /usr/lib/perl5/site_perl/5.8.5/SQL/Statement.pm line 1777, <G
+EN3> line 2.
 [for Statement "update bug set b = 1 + 1"] at 669178.pl line 9.
[...]

$ sudo patch /usr/lib/perl5/site_perl/5.8.5/SQL/Statement.pm sql-patch
patching file /usr/lib/perl5/site_perl/5.8.5/SQL/Statement.pm
Hunk #1 succeeded at 1762 (offset 5 lines).

$ rm bug
rm: remove regular file `bug'? y

$ perl 669178.pl
$ cat bug
a,b
1,1
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