Question about sql query

[A.V.E]

Hello. I have been importing products from csv-file without categories.

Now I'm fiddling around and have this situation: som products (lets say id 15,16,17) have got category, but all have position 0.

Actually there are bigger amount.

I found a query to alter the position semi-manually:

UPDATE ps_category_product INNER JOIN (SELECT id_product FROM ps_category_product WHERE id_product in(15,16,17) and position = 0 LIMIT 1) as t2 using(id_product) SET position = 1;

This is a way where the updates are limited to one row.

But I wanted to make it more automatic and tried:

UPDATE ps_category_product INNER JOIN (SELECT id_product FROM ps_category_product WHERE id_product in(15,16,17) and position = 0 LIMIT 1) as t2 using(id_product) SET position = SELECT MAX(position)+1 FROM ps_category_product as t3 WHERE id_product IN (15,16,17);

But it doesn't work, even though the query

SELECT MAX(position)+1 FROM ps_category_product as t3 WHERE id_product IN (15,16,17);

works.

I wonder why.

[musicmaster]

It would be much easier with product_sort from Prestools (it is free).

I would need to think really hard to think up the right query. This is the kind of question you should ask on a Mysql forum.