where price > 1500 and (title = 'Perl' or title = 'Ruby')

my $where = $dbi->where;
my $price = 1500;
my $titles = ['Perl', 'Ruby'];
my $clause = ['and',
  'price > :price'
  ['or', ('title = :title') x @$titles],
];
my $param = {price => $price, title => $titles};
$where->clause($clause);
$where->param($param);

where date > '2010-01-01' and date < '2010-03-31'

my $where = $dbi->where;
my $start_date = '2010-01-01';
my $end_date   = '2010-03-31';
my $clause = ['and', ':date{>}', ':date{<}'}];
my $param = {
  date => [
    $start_date // $dbi->not_exists,
    $end_date // $dbi->not_exists
  ]
};
$where->clause($clause);
$where->param($param);