Update in a join with sub-query - mysql

Question

UPDATE item t
INNER JOIN ( SELECT
item_name,
MAX( item_keyword ) AS item_keyword
FROM item
WHERE ca_id2 = '2010'
GROUP BY item_name
) s ON t.item_name = s.item_name
SET t.item_keyword = s.item_keyword
WHERE t.ca_id2 ='3010'
The error is:
1064 - 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 'SELECT item_name, max(item_keyword) AS item_keyword
FROM item
MySQL version 4.0.22 What is the reason for the failure?

Answer 1

I tried to construct your query based on
http://www.xaprb.com/blog/2006/06/23/how-to-select-from-an-update-target-in-mysql/
UPDATE item t
SET t.item_keyword =
( SELECT MAX( i.item_keyword ) AS item_keyword
FROM ( SELECT item_keyword, item_name, cd_id2 FROM item ) AS i
WHERE t.item_name = i.item_name
AND i.cd_id2 = '2010'
GROUP BY i.item_name
)
WHERE t.ca_id2 ='3010'
Or you can try this version too
UPDATE item t
INNER JOIN ( SELECT item_keyword, item_name, cd_id2 FROM item ) AS i
SET t.item_keyword =
( SELECT MAX( i.item_keyword ) AS item_keyword
FROM i
WHERE t.item_name = i.item_name
AND i.cd_id2 = '2010'
GROUP BY i.item_name
)
WHERE t.ca_id2 ='3010'
Sorry, I don't have MySQL 4 around, so you have to test the above queries.
Other readings:
http://dev.mysql.com/doc/refman/4.1/en/update.html
http://dev.mysql.com/doc/refman/4.1/en/rewriting-subqueries.html
If the above queries don't work, you can try using a temporary table instead of the subselect:
http://sqlfiddle.com/#!2/13ccb/1
CREATE TEMPORARY TABLE s
SELECT item_name,
MAX( item_keyword ) AS item_keyword
FROM item
WHERE cd_id2 = '2010'
AND item.item_name IN ( SELECT item_name FROM item WHERE item.ca_id2='3010')
GROUP BY item_name;
UPDATE item t
INNER JOIN s ON t.item_name = s.item_name
SET t.item_keyword = s.item_keyword
WHERE t.ca_id2 ='3010';
DROP TEMPORARY TABLE s;