Wordpress wpdb query

function artists_search_country($country_alt){
global $wpdb;
$querystr = "
    SELECT wposts.*, meta1.meta_value as meta_value1, meta2.meta_value as meta_value2, meta3.meta_value as meta_value3
    FROM $wpdb->posts wposts, $wpdb->postmeta meta1, $wpdb->postmeta meta2, $wpdb->postmeta meta3
    WHERE (wposts.ID = meta1.post_id
    	   AND wposts.ID = meta2.post_id
    	   AND wposts.ID = meta3.post_id
    )
    AND (
    	(
    		meta1.meta_key = '_artist_country' AND meta1.meta_value = '$country_alt')
   		OR
    	(meta2.meta_key = '_artist_country_sub' AND meta2.meta_value = '$country_alt')
    	)
    AND meta3.meta_key = '_artist_artist_last_name'
	AND wposts.post_status = 'publish'
	AND wposts.post_type = 'artists'
	ORDER BY meta3.meta_value ASC
    ";
$myposts = $wpdb->get_results($querystr, OBJECT);
return $myposts;
}