表1: Person
+-------------+---------+ | 列名 | 类型 | +-------------+---------+ | PersonId | int | | FirstName | varchar | | LastName | varchar | +-------------+---------+ PersonId 是上表主键
表2: Address
+-------------+---------+ | 列名 | 类型 | +-------------+---------+ | AddressId | int | | PersonId | int | | City | varchar | | State | varchar | +-------------+---------+ AddressId 是上表主键
编写一个 SQL 查询,满足条件:无论 person 是否有地址信息,都需要基于上述两表提供 person 的以下信息:
FirstName, LastName, City, State
select p.FirstName, p.LastName, a.City,a.State from Person p left join Address a on p.PersonId = a.PersonId
176、
编写一个 SQL 查询,获取 Employee
表中第二高的薪水(Salary) 。
+----+--------+ | Id | Salary | +----+--------+ | 1 | 100 | | 2 | 200 | | 3 | 300 | +----+--------+
例如上述 Employee
表,SQL查询应该返回 200
作为第二高的薪水。如果不存在第二高的薪水,那么查询应返回 null
。
+---------------------+ | SecondHighestSalary | +---------------------+ | 200 | +---------------------+
select max(salary) as SecondHighestSalary from Employee where salary<(select max(Salary) from Employee)
原文地址:https://www.cnblogs.com/qiuyuyu/p/9148147.html
时间: 2024-11-07 16:51:59