custom post type - How to order by multiple meta keys? -

i’m using custom loop display events on page, fine ordering event start date using below:

$args = array(      'post_type' => 'event',     'order' => 'asc',     'orderby' => 'meta_value',     'meta_key' => '_event_start_date'); $loop = new wp_query( $args ); 

but meta_key option allows 1 value. how use 2 values (_event_start_date , _event_start_time)?

this wordpress added support in 4.2: https://make.wordpress.org/core/2015/03/30/query-improvements-in-wp-4-2-orderby-and-meta_query/

in case you'll want this:

$args = array(     'post_type'  => 'event',     'meta_query' => array(         'relation' => 'and',         'event_start_date_clause' => array(             'key'     => '_event_start_date',             'compare' => 'exists',         ),         'event_start_time_clause' => array(             'key'     => '_event_start_time',             'compare' => 'exists',         ),      ),     'orderby' => array(         'event_start_date_clause' => 'asc',         'event_start_time_clause' => 'asc',     ), );  $loop = new wp_query( $args );