Mine

select count(p.products_id) as total from products_description pd, products p left join manufacturers m on p.manufacturers_id = m.manufacturers_id, products_to_categories p2c left join specials s on products.products_id = s.products_id where p.products_status = '1' and p.products_id = p2c.products_id and pd.products_id = p2c.products_id and pd.language_id = '1' and p2c.categories_id = '21'

results in:

1054 - Unknown column 'p.products_id' in 'on clause'