MySQL Truncated incorrect DOUBLE value error

Question

I'm trying to create a MySQL query to update all of the product variations tax class in Woocommerce.

Using the query below I keep getting this error and its not something I've come across before, google seems to offer a variety of answers but I'm unable to relate the fix to my query.

I'm getting the error - #1292 - Truncated incorrect DOUBLE value: 'product'?

I don't understand where the value of product comes from in the error?

UPDATE wp_postmeta a 
   JOIN wp_posts b ON b.id = a.post_id  
   SET a.meta_value = 'test456'

WHERE b.post_type = 'product_variation' & a.meta_key = '_tax_class'

Thanks for reading

Answer 1

Try this:

UPDATE wp_postmeta a 
JOIN wp_posts b ON b.id = a.post_id  
SET a.meta_value = 'test456'
WHERE b.post_type = 'product_variation' and a.meta_key = '_tax_class'