题解 | #列出供应商及其可供产品的数量#
列出供应商及其可供产品的数量
http://www.nowcoder.com/practice/17f22851cf204019b51a36761a3afc79
select v.vend_id,if(prod_num is null,0,prod_num) as prod_id
from Vendors as v left join
(select vend_id,count(*) as prod_num from Products group by vend_id) as p
on v.vend_id = p.vend_id
order by v.vend_id;
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