QUERY:
drop table #foot
create table #foot (
id int primary key not null,
name varchar(50) not null
)
go
drop table #note
create table #note (
id int primary key not null,
note varchar(MAX) not null,
foot_id int not null references #foot(id)
)
go
insert into #foot values
(1, 'Joe'), (2, 'Mike'), (3, 'Rob')
go
insert into #note (id, note, foot_id) values (1, 'Joe note 1', 1)
go
insert into #note (id, note, foot_id) values(2, 'Joe note 2', 1)
go
insert into #note (id, note, foot_id) values(3, 'Mike note 1', 2)
go
select F.name, N.note, N.id
from #foot F left outer join #note N on N.foot_id=F.id
结果:
问题:
如何为每个主记录(#foot)创建一个视图/查询,以及最近插入的详细信息(#note)中的字段(如果有)?
目标:
(注意:我告诉哪一个最新的方式是新记录的ID会更高)
答案 0 :(得分:1)
select t.name, t.note, t.id
from (select F.name, N.note, N.id,
ROW_NUMBER() over(partition by F.id order by N.id desc) as RowNum
from #foot F
left outer join #note N
on N.foot_id=F.id) t
where t.RowNum = 1
答案 1 :(得分:1)
假设在#note表中创建的ID总是增量的(通过使用IDENTITY或通过控制插入来总是按最大值递增),您可以使用以下查询(使用等级函数):
WITH Dat AS
(
SELECT f.name,
n.note,
n.id,
RANK() OVER(PARTITION BY n.foot_id ORDER BY n.id DESC) rn
FROM #foot f LEFT OUTER JOIN #note n
ON n.foot_id = f.id
)
SELECT *
FROM Dat
WHERE rn = 1