Another thing I like to avoid is the dreaded and error-prone counting of placeholders. To accomplish this goal I build an array of fields I want, and use it multiple times. Example:

    my @keys = qw(time_value hour_24 minute second hour_12 am_pm);

    my %time = (
      time_value => "2:30:12pm",
      hour_24    => 14,
      hour_12    =>  2,
      minute     => 30,
      second     => 12,
      am_pm      => "pm"
    );

    my $sql  = "INSERT INTO"
             . "   time (" . join(",", @keys)         . ")"
             . " VALUES (" . join(",", ('?') x @keys) . ")";

    my $sth = $dbh->prepare($sql);
    $sth->execute(@time{@keys});
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Note I keep the values I'm executing in a hash with keys matching the field names. This allows me to use a hash slice so even the execute() call is guaranteed to match.