SQL獲取其他值的MAX

Question

我想弄清楚如何選擇一個表，該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

我希望它顯示最高工資的人，所以它應該顯示

Person1

我嘗試對max函數使用where，但是它似乎失敗了。 這些組函數讓我感到很困惑。 我想我問的更多的是如何使用組函數作為約束。 因為我之前有類似的問題。

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，請嘗試使用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

該解決方案幾乎可以在任何數據庫系統中工作：

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達式（例如SQL Server 2005和更高版本）的DBMS，則此問題會更容易。 此解決方案將僅顯示一個名稱，並忽略聯系：

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

此解決方案將顯示所有與最高薪資相匹配並包含平局的人：

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