使用帶有左連接的子查詢和來自另一個表的group_concat的更新字段

Question

我正在使用下一個代碼，但它失敗了，我不知道爲什麼。

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

在MySQL中加入條款成爲第一

，（不要從需要）和設置的條款和

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