As Herkum suggested, you can't simply use Perl regexes in SQL. But based on what you're trying to do, you probably don't need regexes anyway. You can use LIKE. Also, you're best off binding your params rather than including variables in your SQL:

my $data = qq(
SELECT catname, path
  FROM categories
 WHERE path LIKE ?
   AND path != ?
);
my $sth = $dbh->prepare($data);
$sth->execute( "$path/%", $path ) or die $dbh->errstr;
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