Now, there are other ways to work the problem that retain the use of bind variables. Consider:

my @values = qw/1 2 3/;
my $sql = 'select * from foo where x in (' . join(', ', ('?') x @in_va
+lues) . ')';
$dbh->prepare($sql)->execute(@values);
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This preserves the use of placeholders and the benefits therefrom while adapting to the changing number of parameters. You can't avoid constructing the query to fit the data.