2018-11-01
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MySQL分组查询
----group by
查询每个供应商商品数量
select s_id,count(*) as 商品数量(as可省略)
from fruits
group by s_id
order by count (*) desc;
排序总是在最后
查询供应商品数量少于两个的供应商id
对于分组结果进行筛选使用having子句
select s_id,count(*) as 商品数量(as可省略)
from fruits
group by s_id
having count(*)<2
order by count (*) desc;






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