基本的SQL查詢的問題

Question

我有以下查詢：

SELECT  
    Base.ReportDate, 
    Base.PropertyCode, 
    Base.FirstName, 
    Base.MiddleName, 
    Base.LastName, 
    Person.FirstName, 
    Person.MiddleName, 
    Person.LastName 
FROM LeaseT INNER JOIN 
    Base ON LeaseT.LeaseID = Base.LeaseID INNER JOIN 
    Person ON LeaseT.TenantID = Person.ID 

工作正常，但有可能在「人」表基表的每個記錄是0到「N」的人，但只有我想要爲每個'基本'記錄準確地返回1（哪個不重要，但具有最低Person.ID的記錄）是合理的選擇。如果person表中有0行，我仍然需要返回該行，但'person'字段的值爲空。

我該如何構建SQL來做到這一點？

謝謝。

編輯：是的，這些表格可能結構不正確，但此時重組是不可能的 - 必須配合現有的功能。

Answer 1

工作的呢？

SELECT  
    Base.ReportDate, 
    Base.PropertyCode, 
    Base.FirstName, 
    Base.MiddleName, 
    Base.LastName, 
    Person.FirstName, 
    Person.MiddleName, 
    Person.LastName 
FROM Base 
LEFT JOIN (
    SELECT LeaseID, MIN(TenantID) AS [TenantID] 
    FROM LeaseT 
    GROUP BY LeaseID) AS [LeaseT_SinglePerson] ON Base.LeaseID = [LeaseT_SinglePerson].LeaseID 
LEFT JOIN Person ON [LeaseT_SinglePerson].TenantID = Person.ID 

Answer 2

使用左連接

Answer 3

下面可能對你有幫助

SELECT  
    Base.ReportDate, 
    Base.PropertyCode, 
    Base.FirstName, 
    Base.MiddleName, 
    Base.LastName, 
    d.FirstName, ou 

    d.MiddleName, 
    d.LastName 
FROM LeaseT INNER JOIN 
    Base ON LeaseT.LeaseID = Base.LeaseID INNER JOIN 
left outer join 
(select min(personid) as ID from person group by personid) as d 
on 
LeaseT.TenantID = d.ID 
left outer join 
(select FirstName, 
    MiddleName, 
    LastName from person) d1 
on 
    LeaseT.TenantID = d1.ID