php - How to save backslashes in database via wordpress -

i use wordpress , want save pattern ".*www.site.com" in database.

$wpdb->query("insert $wpdb->postmeta (`post_id`, `meta_key`, `meta_value`) values (1, 'pattern', '.*www\.site\.com')"); 

it saves without backslashes ".*www.site.com".

how solve it?

in php can print backslash following:
echo 'abc\xyz'; //use single slash if using single quotes(')
or

echo "abc\\xyz"; //use double slash if using double quotes; 

so write query as:
$wpdb->query("insert $wpdb->postmeta (post_id,meta_key,meta_value) values (1, 'pattern', '.*www\\.site\\.com')");