my $sth = $dbh->prepare(q{
  INSERT
    INTO table
         (col1, col2, col3)
  VALUES (?, ?, ?)
});

##</code><code>##

my $tuple = $dbh->selectrow_array(q{
    SELECT col1
      FROM table1
     WHERE col1 = col2
       AND col2 = ?
     LIMIT 1
  },
  {},
  $someval,
);

##</code><code>##

my $sth_get_id = $dbh->prepare(q{
  SELECT id
    FROM contact
   WHERE email = ?
   LIMIT 1
});

foreach my $email (@emails) {
  my $id = $dbh->selectrow_array($sth_get_id, {}, $email);

  print "$email -> $id\n";
}

##</code><code>##

my $emails = $dbh->selectcol_arrayref(q{
    SELECT email
      FROM contact
     WHERE id BETWEEN ? AND ?
  },
  {},
  1, 
  100,
);

foreach my $email (@$emails) { ...