다른 테이블의 왼쪽 조인 및 group_concat이있는 하위 쿼리를 사용하는 업데이트 필드

Question

다음 코드를 사용하고 있지만 실패하고 이유를 모르겠습니다. 무엇을

UPDATE pd 
SET pd.meta_categories = x.categories 
FROM t_product_description pd 
JOIN (
    SELECT p.product_id AS productid, GROUP_CONCAT(cd.name SEPARATOR ' ') AS categories 
    FROM t_product AS p 
    LEFT JOIN t_product_to_category AS p2c ON (p2c.product_id = p.product_id) 
    LEFT JOIN t_category_description AS cd ON (cd.category_id = p2c.category_id) 
    GROUP BY p.product_id 
) x ON pd.product_id = x.productid 

Answer 1

조인 절은 최초로 MySQL의에서

, (에서 필요하지 않습니다)와 SET 절과

UPDATE t_product_description pd 
JOIN (
    SELECT p.product_id AS productid, GROUP_CONCAT(cd.name SEPARATOR ' ') AS categories 
    FROM t_product AS p 
    LEFT JOIN t_product_to_category AS p2c ON (p2c.product_id = p.product_id) 
    LEFT JOIN t_category_description AS cd ON (cd.category_id = p2c.category_id) 
    GROUP BY p.product_id 
) x ON pd.product_id = x.productid 
SET pd.meta_categories = x.categories