力扣LeetCode - SQL Server

182.编写一个 SQL 查询，查找 Person 表中所有重复的电子邮箱。

示例：

±—±--------+
| Id | Email |
±—±--------+
| 1 | [email protected] |
| 2 | [email protected] |
| 3 | [email protected] |
±—±--------+
根据以上输入，你的查询应返回以下结果：

±--------+
| Email |
±--------+
| [email protected] |
±--------+
说明：所有电子邮箱都是小写字母。

select Email from Person group by Email having count(Email) > 1

183.从不订购的客户

select Name as Customers from Customers where Customers.id not in (select customerid from orders)

表联结
(转载来源：mayi2019)

select c.Name as Customers from Customers as c left join orders as o on o.customerID = c.ID where o.ID is Null