UPDATE query with left join not working

Question

Hi I have tried different things to get it to work apparently I'm doing something wrong. Probably a small something.

So I'm trying to update a value from a left join tabel this is the select query witch works fine. But now I want to update the value.

SELECT 
categories.categories_id,
cd.categories_name as cat_name, 
p2c.products_id as p2c_id, 
p2c.categories_id , 
p.products_id as p_id, 
pa.products_id as pa_id, 
pa.c_content_id as pa_c_content_id, 
pa.*,
c.group_id, c.content

FROM categories
left join (categories_description as cd) on(categories.categories_id = cd.categories_id)
left join (products_2_categories as p2c) on(categories.categories_id = p2c.categories_id)
left join (products as p) on (p2c.products_id = p.products_id)
left join (products_attributes as pa) on (p.products_id = pa.products_id and pa.attribute_items_id = 7)
left join (content as c) on(pa.c_content_id = c.group_id)

WHERE p2c.products_id IS NOT NULL AND pa.products_id IS NOT NULL AND (categories.categories_id = 42 OR categories.parent_id in(42)) ORDER BY cd.categories_name ASC , p2c.products_id ASC; 

This is the update query I'm trying to execute.

UPDATE content 
FROM categories AS ca
LEFT JOIN(categories_description AS cd) ON(ca.categories_id =    cd.categories_id)
LEFT JOIN(products_2_categories AS p2c) ON(ca.categories_id = p2c.categories_id)
LEFT JOIN(products AS p) ON(p2c.products_id = p.products_id)
LEFT JOIN(products_attributes AS pa) ON(p.products_id = pa.products_id AND pa.attribute_items_id = 7)
LEFT JOIN(content AS c) ON(pa.c_content_id = c.group_id)

SET content.content = ''

WHERE p2c.products_id IS NOT NULL 
AND pa.products_id IS NOT NULL 
AND (ca.categories_id = 42 OR ca.parent_id in(42)) 
ORDER BY cd.categories_name ASC , p2c.products_id ASC; 

Can anybody help me out a bit here I don't understand what I'm doing wrong.

Answer 1

Well, it does not hurt to observe the syntax for update for a start:

UPDATE categories AS ca
LEFT JOIN(categories_description AS cd) ON(ca.categories_id =    cd.categories_id)
LEFT JOIN(products_2_categories AS p2c) ON(ca.categories_id = p2c.categories_id)
LEFT JOIN(products AS p) ON(p2c.products_id = p.products_id)
LEFT JOIN(products_attributes AS pa) ON(p.products_id = pa.products_id AND pa.attribute_items_id = 7)
LEFT JOIN(content AS c) ON(pa.c_content_id = c.group_id)

SET content.content = ''

WHERE p2c.products_id IS NOT NULL 
AND pa.products_id IS NOT NULL 
AND (ca.categories_id = 42 OR ca.parent_id in(42)); 

Looking at the query in more detail: there is no point in making the joins left joins, since the table you are updating is on the right hand side, so to update it, it should exist. So I would use inner joins instead of left. categories_description table does not seem to influence if content should be updated, so it should be removed from the SQL statement.