Get today total sales

SELECT sum(pm1.meta_value) as total FROM `wp_postmeta` as pm1

INNER JOIN `wp_posts` as p ON p.ID = pm1.post_id

where pm1.meta_key = '_order_total'

and p.post_type = 'shop_order'

and p.post_status IN ( 'wc-completed', 'wc-processing' )

and p.post_date = '2018-12-28'