Speed up an SQL query which uses a FullText Join - mysql

Question

I have a situation where I need to JOIN and inner query from a products database, grouping items by name and then using the name column to perform the join, thus:
SELECT p.*, p3.variants, sl.id, l.name as locationName FROM products p
LEFT JOIN (SELECT item, count(DISTINCT id) as variants FROM products GROUP BY item) p3
ON p3.item = p.item
LEFT JOIN stockLevels sl ON sl.id=p.id
LEFT JOIN locations l ON l.id=sl.stockLocation AND l.showStock='1'
WHERE p.id='10459' GROUP BY p.id
Having messed around with the order of JOIN and the query itself, I have determined that having this inner table being created first and performing the first required join makes a difference to the speed of the query, but the inner join (SELECT item, count(DISTINCT id) as variants FROM products GROUP BY item) is giving (at present) 7034 rows, which is needless as only about 5 are required.
If I modify the inner join to:
(SELECT item, count(DISTINCT id) as variants
FROM products *WHERE item LIKE '%SOME VALUE%'* GROUP BY item)
This obviously reduces the number of rows returned by that inner join, and it is roughly twice as fast.
But, I can't do this as I don't have a known value to use for the inner where clause.
Is there any way I can bring the results from the outer table into the inner and produce an inner query that references the outer, ie:
SELECT p.*, p3.variants, sl.id, l.name as locationName FROM products p
LEFT JOIN (SELECT item, count(DISTINCT id) as variants
FROM products *WHERE item LIKE p.item * GROUP BY item) p3 << New Where Clause
ON p3.item = p.item
LEFT JOIN stockLevels sl ON sl.id=p.id
LEFT JOIN locations l ON l.id=sl.stockLocation AND l.showStock='1'
WHERE p.id='10459' GROUP BY p.id
I know that what I have written above won't work, and understand why, but is there a way I could achieve something on these lines?
With the number of records in my database at the moment, this actually isn't an issue, the data is returned very quickly, but I can imagine that in time, when the data grows, it could be.
Note, I did look at making a parentId integer column, instead of grouping by the FullText item but there are lots of other issues within my application, and it didn't seem to speed the query up anyway, for the same reasons as listed above, the inner still had to return all rows
Also Note, this is MySQL
If it helps at all here's the output from EXPLAIN

Answer 1

You can put a correlated subquery in the SELECT clause:
SELECT p.*, sl.id, l.name as locationName,
(SELECT COUNT(distinct id)
FROM products p3
WHERE p3.item = p.item) as variants
FROM products p
LEFT JOIN stockLevels sl ON sl.id=p.id
LEFT JOIN locations l ON l.id=sl.stockLocation AND l.showStock='1'
WHERE p.id='10459' GROUP BY p.id

Answer 2

If only 5 are required, just do it the classic way:
SELECT
p.*,
p3.variants,
sl.id,
l.name as locationName,
(SELECT count(DISTINCT id)
FROM products
WHERE item LIKE p.item GROUP BY item) total
FROM products p
LEFT JOIN stockLevels sl
ON sl.id=p.id
LEFT JOIN locations l
ON l.id=sl.stockLocation AND l.showStock='1'
WHERE p.id='10459' GROUP BY p.id
Here you can access the parent table.