Wordpress Query Parameters Date Parameter

Returns posts dated December 12, 2012:
$query = new WP_Query( 'year=2012&monthnum=12&day=12' );

or:
$args = array(
    'date_query' => array(
        array(
            'year'  => 2012,
            'month' => 12,
            'day'   => 12,
        ),
    ),
);
$query = new WP_Query( $args );
Returns posts for today:
$today = getdate();
$query = new WP_Query( 'year=' . $today['year'] . '&monthnum=' . $today['mon'] . '&day=' . $today['mday'] );

or:
$today = getdate();
$args = array(
    'date_query' => array(
        array(
            'year'  => $today['year'],
            'month' => $today['mon'],
            'day'   => $today['mday'],
        ),
    ),
);
$query = new WP_Query( $args );

Returns posts for this week:
$week = date( 'W' );
$year = date( 'Y' );
$query = new WP_Query( 'year=' . $year . '&w=' . $week );

or:
$args = array(
    'date_query' => array(
        array(
            'year' => date( 'Y' ),
            'week' => date( 'W' ),
        ),
    ),
);
$query = new WP_Query( $args );

Return posts between 9AM to 5PM on weekdays
$args = array(
    'date_query' => array(
        array(
            'hour'      => 9,
            'compare'   => '>=',
        ),
        array(
            'hour'      => 17,
            'compare'   => '<=',
        ),
        array(
            'dayofweek' => array( 2, 6 ),
            'compare'   => 'BETWEEN',
        ),
    ),
    'posts_per_page' => -1,
);
$query = new WP_Query( $args );

Return posts from January 1st to February 28th
$args = array(
    'date_query' => array(
        array(
            'after'     => 'January 1st, 2013',
            'before'    => array(
                'year'  => 2013,
                'month' => 2,
                'day'   => 28,
            ),
            'inclusive' => true,
        ),
    ),
    'posts_per_page' => -1,
);
$query = new WP_Query( $args );

Note that if a strtotime()-compatible string with just a date was passed in the before parameter, this will be converted to 00:00:00 on that date. In this case, even if inclusive was set to true, the date would not be included in the query. If you want a before date to be inclusive, include the time as well, such as 'before' => '2013-02-28 23:59:59', or use the array format, which is adjusted automatically if inclusive is set.
Return posts made over a year ago but modified in the past month
$args = array(
    'date_query' => array(
        array(
            'column' => 'post_date_gmt',
            'before' => '1 year ago',
        ),
        array(
            'column' => 'post_modified_gmt',
            'after'  => '1 month ago',
        ),
    ),
    'posts_per_page' => -1,
);
$query = new WP_Query( $args );