WP_Query Ordered By Multiple Meta Keys

wp-query-orderby-muliple-meta-keys.php

<?php
/* build a new wp_query */
	$classes = new WP_Query(
		array(
			'post_type'			=> 'wpmark_class_time', // post type to query
			'posts_per_page'	=> -1, // get all the posts not limited
			'meta_query'		=> array(
				'relation'	=> 'AND',
				'day' => array( // give the first meta key array an array key
					'key'		=> '_wpmark_day',
					'compare'	=> 'EXISTS',
					'type'		=> 'NUMERIC'
				),
				'location' => array(
					'key'		=> '_wpmark_location',
					'value' 	=> $post->ID,
					'compare'	=> 'EXISTS'
				),
				'start_time' => array(
					'key'		=> '_wpmark_start_time',
					'compare'	=> 'EXISTS',
					'type'    => 'NUMERIC',
				)
			),
			// order by using the meta array keys to reference them
			'orderby'			=> array(
				'day'			=> 'ASC',
				'start_time'	=> 'ASC'
			),
			'fields'			=> 'ids'
		)
	);
?>