Adding a Subquery to a Query in SQL - mysql

Question

I have a query that works very well. Let me start with it:
Edit: The SQL has been updated. I get 0 in every row.
SELECT i.item, i.user_id, u.username,
(COALESCE(r.ratetotal, 0)) AS total,
(COALESCE(c.commtotal, 0)) AS comments,
(COALESCE(r.rateav, '50%')) AS rate,
(COALESCE(x.wasRated, '0')) AS wasRated
FROM items AS i
LEFT JOIN master_cat AS c
ON (c.cat_id = i.cat_id)
LEFT JOIN users AS u
ON u.user_id = i.user_id
LEFT JOIN
(SELECT item_id,
COUNT(item_id) AS ratetotal,
AVG(rating) AS rateav
FROM ratings GROUP BY item_id) AS r
ON r.item_id = i.item_id
LEFT JOIN
(SELECT item_id,
COUNT(item_id) AS commtotal
FROM reviews GROUP BY item_id) AS c
ON c.item_id = i.item_id
LEFT JOIN
(SELECT xu.user_id, ra.item_id, '1' AS wasRated
FROM users AS xu
LEFT JOIN ratings AS ra
ON ra.user_id = xu.user_id
WHERE xu.user_id = '1') AS x
ON x.user_id = u.user_id
AND x.item_id = r.item_id
WHERE c.category = 'Movies'
ORDER by i.item ASC;
I need to add one more function to it, where you see AS x
Basically, there are three tables here that are important. items, reviews and ratings. In the top portion you see there are subqueries that are taking statistics such as averages and totals for each item.
I need a final query that is tied to user_id, item_id and rate_id (in ratings). In the end result, where it list each item and the stats with it, I want one more column, a simple true or false if logged in user has rated it. So I need something like this:
SELECT ???
FROM ratings AS r
WHERE r.user_id = '{$user_id}'
(user_id of logged in user is passed in from PHP.`)
How can I make a subquery that gives me that last bit of info, but puts it in each row of items in the parent query?

Answer 1

Add this to the parent query.
, coalesce(x.WasRated, 'false') as WasRated
Your x subquery is:
(select users.user_id
, ratings.item_id
, 'true' WasRated
from users join ratings on user.user_id = ratings.user_id
where users.user_id = the one for the logged in user
) x on x.user_id = users.user_id
and x.item_id = ratings.item_id
or something like it.