Question

以下代码返回：

personID  lastname  firstname  number
-------------------------------------
  17520   doe       john       0192

代码：

select 
    personID, lastname, firstname, number
from 
    (select distinct
         max(sm.personID) as personID, 
         sm.lastName, 
         ISNULL(sm.alias, sm.firstName) as firstname,       
         max(sm.schoolNumber) as number, 
         max(assignmentID) as assignmentID
     from 
         staffmember sm
     where 
         (sm.endDate >= GetDate() or sm.endDate is null)
         and (sm.startDate <= GetDate())
     group by 
         sm.lastName, sm.firstName, sm.alias) as query
where 
    1 = 1

如果我拉出子查询并从schoolNumber和assignmentID中删除最大聚合，然后将assignmentID添加到选择中，以使查询看起来像这样：

select distinct
max(sm.personID) as personID, 
sm.lastName, 
ISNULL(sm.alias, sm.firstName) as firstname,
sm.schoolNumber as number, 
sm.assignmentID as assignmentID
from staffmember sm
where (sm.endDate >= GetDate() or sm.endDate is null)
and (sm.startDate <= GetDate())
and personID = '17520'
group by sm.lastName, sm.firstName, sm.alias, sm.schoolNumber, sm.assignmentID

查询返回：

personID  lastname  firstname  number  assignmentID
----------------------------------------------------
17520     doe       john       0192    1354
17520     doe       john       0103    1538

我需要原始查询才能返回：

personID  lastname  firstname  number
-------------------------------------
17520     doe       john       0103

Answer 1

您可以在下面使用相关子查询尝试

select sm.personID as personID, sm.lastName, ISNULL(sm.alias, sm.firstName) as firstname,
sm.schoolNumber as number, 
sm.assignmentID as assignmentID
from staffmember sm
where (sm.endDate >= GetDate() or sm.endDate is null)
and (sm.startDate <= GetDate())
and personID = '17520' 
and assignmentID in 
    (select max(assignmentID) from staffmember sm1 where sm.personID =sm1.personid 
      and sm1.personID = '17520')

SQL从子查询返回最大值

1 个答案: