mysql 分组 having_MySQL分组子句having详解
假设
按照 select pinpai,count(*) as 数量,max(price) as 最高价,min(price) as 最低价,avg(price) as 平均价 ,sum(price) as 总价,chandi from product group by pinpai;搜索是不正确的搜索但不报错
having
是什么？
类比 where
定义:对分组结果数据进行筛选
区别：
Where是对原始数据进行筛选
having 对分组之后进行筛选
例1 找出平均价大于5000的品牌信息
select pinpai,count(*) as 数量,max(price) as 最高价,min(price) as 最低价,avg(price) as 平均价 ,sum(price) as 总价 from product group by pinpai having 平均价>5000;
例2 找出商品数超过2个的品牌信息
select pinpai,count(*) as 数量,max(price) as 最高价,min(price) as 最低价,avg(price) as 平均价 ,sum(price) as 总价 from product group by pinpai having 数量>2;
波利亚《怎样解题》：你能否重新叙述这个问题？
select pinpai,count(*) as 数量,max(price) as 最高价,min(price) as 最低价,avg(price) as 平均价 ,sum(price) as 总价 from product group by pinpai having count(*)>2;
假设 按照 select pinpai,count(*) as 数量,max(price) as 最高价,min(price) as 最低价,avg(price) as 平均价 ,sum(price) as 总价,chandi from product group by pinpai;搜索是不正确的搜索但不报错 having 是什么？ 类比 where 定义:对分组结果数据进行筛选 区别： Where是对原始数据进行筛选 having 对分组之后进行筛选 例1 找出平均价大于5000的品牌信息 select pinpai,count(*) as 数量,max(price) as 最高价,min(price) as 最低价,avg(price) as 平均价 ,sum(price) as 总价 from product group by pinpai having 平均价>5000; 例2 找出商品数超过2个的品牌信息 select pinpai,count(*) as 数量,max(price) as 最高价,min(price) as 最低价,avg(price) as 平均价 ,sum(price) as 总价 from product group by pinpai having 数量>2; 波利亚《怎样解题》：你能否重新叙述这个问题？ select pinpai,count(*) as 数量,max(price) as 最高价,min(price) as 最低价,avg(price) as 平均价 ,sum(price) as 总价 from product group by pinpai having count(*)>2;