用SQL返回兩個單獨的表的輸出

Question

我有兩個表products和assets。他們加入了表assets_products。

我需要返回一個表，其中包含products和assets中的所有行，同時還顯示assets_products中兩個關聯行的數量。

並非所有產品都有資產，反之亦然，我需要用零計數來顯示。

例如：

product asset count 
foo  x  1 
bar  x  0 
foo  y  2 
bar  y  1 

Answer 1

select products.product, 
     assets.asset, 
     COUNT(assets_products.id) as count 
from assets 
cross join products 
left join assets_products 
    on (assets_products.asset_id = assets.id and 
     assets_products.product_id = products.id) 
group by products.product, assets.asset 

Answer 2

select p.product,a.asset,count(*) 
from product p 
full outer join product_asset pa 
on pa.product_id=p.product_id 
full outer join asset a 
on a.asset_id=pa.asset_id 
group by p.product_id,a.asset_id