解法(1):思路为先查询出订购的客户再使用not in查询出不包含订购客户的其他人也就是从来不订购的客户 查询出订购的客户语句:
select a.Id from Customers as a,Orders as b where b.CustomerIda.Id再使用not in 查询 不再里面的客户
select Name as Customers fr…
此题是查询出销售额最高的人的ID 首先我们通过语句查询出最高的销售额
select top 1 sum(price) from Sales group by seller_id order by sum(price) desc然后我们通过查询总和的值和 最高销售额相等的ID即可
select seller_id from Sales group by seller_id having sum(p…
解法(1):思路为先查询出查询出重复的ID并且取最小值 select min(Id) Id,Email from Person group by Email或者
Select min(Id) as Id,distinct Email from Person然后删除不在ID为此里面的值
delete from Person where Id not in(select Id from ( select min(Id…
0. 简介GMM和Kmeans一样也属于聚类,其算法训练流程也十分相似,Kmeans可认为是“硬聚类”,GMM是“软聚类”。给定数据集X,Kmeans算法流程是这样的----- a 初始化:随机初始k个中心(即k个点,记为μ…
测试数据库查询语句的执行效率declare d datetimeset dgetdate()select * from ordersselect [语句执行花费时间(毫秒)]datediff(ms,d,getdate())转载于:https://www.cnblogs.com/wangxiang/articles/777082.html