Question

我有以下查询：

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，除了Base表中每个记录的'Person'表中可能有0到'N'个人，但我只想为每个'Base'记录返回1个（无关紧要），但Person.ID最低的那个将是一个合理的选择。如果人员表中有0行，我仍然需要返回该行，但“人员”字段的值为空。

我如何构建SQL来做到这一点？

感谢。

编辑：是的，这些表可能没有正确构建，但此时无法进行重组 - 可以使用那里的内容。

Answer 1

以下可能对您有所帮助

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

Answer 2

这有用吗？

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 3

使用左连接

基本的SQL查询问题

3 个答案: