woocommerce-product-attr-all.sql

SELECT p.`ID` AS 'Product ID',
       p.`post_title` AS 'Product Name',
       t.`term_id` AS 'Attribute Value ID',
       REPLACE(REPLACE(tt.`taxonomy`, 'pa_', ''), '-', ' ') AS 'Attribute Name',
       t.`name` AS 'Attribute Value'
FROM `wp_posts` AS p
INNER JOIN `wp_term_relationships` AS tr ON p.`ID` = tr.`object_id`
INNER JOIN `wp_term_taxonomy` AS tt ON tr.`term_taxonomy_id` = tt.`term_id`
AND tt.`taxonomy` LIKE 'pa_%'
INNER JOIN `wp_terms` AS t ON tr.`term_taxonomy_id` = t.`term_id`
WHERE p.`post_type` = 'product'
  AND p.`post_status` = 'publish'
ORDER BY p.`ID`

Full article in https://www.webhat.in/article/woocommerce-tutorial/how-product-attribute-are-stored-in-database/