MySQL update using inner join on a nested query

Question

I'm trying to do this: look up a resource_id from a table items , which has asset_id and resource_id , and use it to set the resource_id field in another table, elements , which also has asset_id and resource_id .

UPDATE t1 SET t1.resource_id = t2.resource_id 
FROM elements t1 INNER JOIN
( SELECT asset_id, resource_id 
  FROM items 
  WHERE resource_id is not null
  GROUP BY asset_id ) t2 
ON t1.asset_id = t2.asset_id; 

I'm getting the very vague message:

ERROR 1064 (42000): You have an error in your SQL syntax; check the 
manual that corresponds to your MySQL server version for the 
right syntax to use near 'FROM elements t1 INNER JOIN
( SELECT asset_id, resource_id 
  FROM items' at line 2

This is in MySQL 5.6.27. Can anyone see what i'm doing wrong?

Thanks, Max

Answer 1

As the error says, your syntax is wrong. Try this:

UPDATE elements as t1  
INNER JOIN
( SELECT asset_id, resource_id 
  FROM items 
  WHERE resource_id is not null
  GROUP BY asset_id ) t2 
ON t1.asset_id = t2.asset_id
SET t1.resource_id = t2.resource_id 

Answer 2

UPDATE elements AS t1,
(SELECT asset_id, resource_id FROM items WHERE resource_id IS NOT NULL GROUP BY asset_id ) AS t2 SET t1.resource_id = t2.resource_id WHERE t1.asset_id = t2.asset_id;