Select only one record from many duplicates - mysql

Question

Hello im using the below query to select some elements from the db.
SELECT *,c.slug AS pslug,d.slug AS catslug
FROM uhhu_virtuemart_products as a
LEFT JOIN uhhu_virtuemart_products_el_gr as d
on a.virtuemart_product_id=d.virtuemart_product_id
LEFT JOIN uhhu_virtuemart_product_categories as b
ON a.virtuemart_product_id = b.virtuemart_product_id
LEFT JOIN uhhu_virtuemart_categories_el_gr AS c
ON b.virtuemart_category_id=c.virtuemart_category_id
WHERE a.virtuemart_product_id = 508
The problem is that a product can have many categories , so this query returns me 3 rows, while i need to take always 1 row for output.
virtuemart_product_categories:
What i want is, when it check for the category here :
LEFT JOIN uhhu_virtuemart_product_categories as b
ON a.virtuemart_product_id = b.virtuemart_product_id
put a LIMIT 1 statement
I tried to use a nested select like this:
SELECT *,c.slug AS pslug,d.slug AS catslug
FROM uhhu_virtuemart_products as a
WHERE uhhu_virtuemart_product_id =
(SELECT virtuemart_product_id
from virtuemart_product_categories
where virtuemart_product_id=508 LIMIT 1)
LEFT JOIN uhhu_virtuemart_categories_el_gr AS c
ON a.virtuemart_category_id=c.virtuemart_category_id
LEFT JOIN uhhu_virtuemart_categories_el_gr as d
on c.virtuemart_category_id=d.virtuemart_category_id
And Like this:
SELECT *,c.slug AS pslug,d.slug AS catslug
FROM uhhu_virtuemart_product_categories as a
LEFT JOIN uhhu_virtuemart_products_el_gr as d
on a.virtuemart_product_id=d.virtuemart_product_id
LEFT JOIN uhhu_virtuemart_categories_el_gr AS c
ON a.virtuemart_category_id=c.virtuemart_category_id
WHERE a.virtuemart_product_id =(
SELECT virtuemart_product_id
from uhhu_virtuemart_product_categories as f
where f.virtuemart_product_id=508
LIMIT 1)
I tried also use SELECT distinct but it didnt work too.I know only the basics of SQL and couldnt find something similar to help me solve this, so i would appreciate your help.
Hope i was clear enough.