更新MySQL数据库列，其中元数据从一行复制到另一行

Question

I've been presented with a situation where I need to update data in a MySQL database column where I copy the data from the column of one row of related data to the same column but in a different row. It is a Wordpress/WooCommerce database table called "wp_woocommerce_order_itemmeta". I want to be able to copy the value of the meta_value where meta_key=_product_id to meta_value column where meta_key=_variation_id whereever the order_item_id numbers match . So, in the screenshot you see that all the order_item_id values are all the same (they are all 8) - I want the 172 in the meta_value column to be copied to the meta_value column where meta_key=_variation_id

https://snag.gy/DMrfXu.jpg

I want to be able to update these by using the _product_id values because I have around 180 products and I can do this rather quickly. I can not, however, do this by including the order_item_id numbers because I have tens of thousands of orders.

The variation ID numbers all came through with the value of 0 after a migration from OpenCart. I'm hoping there is a way to run a query like this.

Answer 1

I figured out the answer to my own question. This is what worked for me:

UPDATE wp_woocommerce_order_itemmeta as wp1, wp_woocommerce_order_itemmeta as wp2 
SET wp2.meta_value = replace(wp2.meta_value,'0','172') 
WHERE wp1.order_item_id = wp2.order_item_id AND wp1.meta_key = '_product_id' 
AND wp2.meta_key = '_variation_id' AND wp1.meta_value='172' AND wp2.meta_value='0';

I hope this might help someone in the future.