If you're going to be using 'IN' a lot, and the set changes, but have a high likelyhood of having the same number of values, you may get better performance by using bind variables. (although, in the cases of numeric ranges, use 'BETWEEN' or <= and >=)

my @set = ($c .. $d);
my $sql =
  'SELECT type FROM dog WHERE number IN ( ?'.(',?' x $#set).') ';
my $sth = $db->prepare($sql)
   $sth->execute(@set);
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