SQL获取其他值的MAX

Question

我想弄清楚如何选择一个表，该表的值是薪水最高的人的ID。

所以如果我有

表格=工作

JobID  Pay
----------
12345  10  
12346  12  
12347  13

table = thePerson

Person   JobID   
--------------
Person1  1  
Person2  2  
Person3  3

table =雇用（FKs）

JobID  PersonID
----------------
12345  2  
12347  1  
12346  3

我希望它显示最高工资的人，所以它应该显示

Person1

我尝试对max函数使用where，但是它似乎失败了。 这些组函数让我感到很困惑。 我想我问的更多的是如何使用组函数作为约束。 因为我之前有类似的问题。

Answer 1

SELECT p.Person
FROM person p JOIN hire h ON p.PersonID = h.PersonID
  JOIN theJobs j ON h.JobID = j.JobID
ORDER BY j.Pay DESC
LIMIT 1;

如果使用的是不支持LIMIT子句的RDBMS，请尝试使用TOP子句：

SELECT TOP 1 p.Person
FROM person p JOIN hire h ON p.PersonID = h.PersonID
  JOIN theJobs j ON h.JobID = j.JobID
ORDER BY j.Pay DESC

Answer 2

该解决方案几乎可以在任何数据库系统中工作：

Select ....
From thePerson As P
    Join    (
            Select H1.PersonId, Max( J1.Pay ) As MaxPay
            From hire As H1
                Join theJobs As J1
                    On J1.JobId = H1.JobID
            Group By H1.PersonId
            ) As PayPerPerson
        On PayPerPerson.PersonId = P.Person
Where Exists    (
                Select 1
                From hire As H2
                    Join theJobs As J2
                        On J2.JobId = H2.JobID
                Where H2.PersonId = P.Person
                Having Max( J2.Pay ) = PayPerPerson.MaxPay
                )

如果使用支持排名功能和公用表表达式（例如SQL Server 2005和更高版本）的DBMS，则此问题会更容易。 此解决方案将仅显示一个名称，并忽略联系：

With RankedPay As
    (
    Select  ...
        , Row_Number() Over( Order By J.Pay Desc ) As Rnk
    From thePerson As P
        Join hire As H
            On H.PersonId = P.Person
        Join theJobs As J
            On J.JobId = H.JobId
    )
Select ...
From RankedPay
Where Rnk = 1

此解决方案将显示所有与最高薪资相匹配并包含平局的人：

With RankedPay As
    (
    Select  ...
        , Rank() Over( Order By J.Pay Desc ) As Rnk
    From thePerson As P
        Join hire As H
            On H.PersonId = P.Person
        Join theJobs As J
            On J.JobId = H.JobId
    )
Select ...
From RankedPay
Where Rnk = 1