Query the woocommerce published products (both base products and variations) that have 0 or no weight assigned.

woocommerce-weightcheck-with-quoteproduct.sql

SELECT weight_info.post_id, weight_info.meta_key, weight_info.meta_value, wp_posts.post_title, quote_info.meta_key, quote_info.meta_value, wp_posts.post_status
FROM wordpress_cappels.wp_postmeta as weight_info
LEFT JOIN wordpress_cappels.wp_posts ON weight_info.post_id = wp_posts.ID
LEFT JOIN wordpress_cappels.wp_postmeta as quote_info ON quote_info.post_id = wp_posts.ID
where 
	weight_info.meta_key like '_weight' and
	quote_info.meta_key like 'quote_product_checkbox' and 
	(weight_info.meta_value like '0' or weight_info.meta_value like '')  and 
	(quote_info.meta_value like 'no' or quote_info.meta_value like '') and
	wp_posts.post_status like 'publish' ;

woocommerce-weightcheck.sql

SELECT wp_postmeta.post_id, wp_posts.post_status, wp_postmeta.meta_key, wp_postmeta.meta_value, wp_posts.post_title 
FROM databasename.wp_postmeta 
LEFT JOIN databasename.wp_posts ON wp_postmeta.post_id = wp_posts.ID
where meta_key like '_weight' and (meta_value like '0' or meta_value like '') and wp_posts.post_status like 'publish';