表连接SELECT语句

求一个表连接SELECT语句！


' 求一个SQL的SELECT语句，用于连接两个表
' 并且依照日期的大小，返回最新的不重复记录，具体期望如下：

' 1、在[Products]表中寻找所有Username等于[Users]表中的Username的记录
' 2、在上述基础上以[Products]表中的CompleteDate字段作为条件获取不重复的唯一记录
' 3、把[Products]得到的结果与表[Users]连接，得到结果集

' 因为[Products]的Username字段中并没出现“李四”的记录
' 因此结果集只需要返回两笔不重复的记录
' 请问这个SELECT语句该如何编写？谢谢！


'  表Users
'  UID    Username    Department
'--------------------------
'    1    张三           生产部
'    2    李四           研发部
'    3    王五           品质部


'  表Products
'--------------------------
'  ProID    Username    Item         CompleteDate
'    1      张三           开料           2012-6-8
'    2      王五           抽检           2012-6-8
'    3      王五           出货检验       2012-6-10
'    4      张三           送检           2012-6-9
'    5      王五           打包装         2012-6-9


'  期望得到结果集
'  UID   Username   Department    ProID   Item      CompleteDate
'---------------------------
'   3      王五          品质部          3     出货检验    2012-6-10
'   1      张三          生产部          4     送检        2012-6-9

[最优解释]
select * from Users a,Products b where a.Username=b.Username
and not eixsts(select 1 from Products where Username=b.Username and CompleteDate>b.CompleteDate)
[其他解释]

SELECT  B.UID,B.Username,B.Department,A.ProID,A.Item,A.CompleteDate 
FROM [Products] A,[Users] B
WHERE A.Username = B.Username
AND NOT EXISTS (
SELECT 1
FROM [Products] C
WHERE A.Username = C.Username
AND C.CompleteDate  &gt; A.CompleteDate 
)

------其他解决方案--------------------

---------------------创建表以及插入数据，开始-----------------------------------
if(object_id('a')is not null) drop table a
go
create table a
(
UID int,
Username varchar(50),
Department varchar(50)
)
go
insert into a
select 1,'张三','生产部' union all
select 2,'李四','研发部' union all
select 3,'王五','品质部'
go

if(object_id('b')is not null) drop table b
go
create table b
(
ProID int,
Username varchar(50),
Item varchar(50),
CompleteDate datetime
)
go
insert into b
select 1,'张三','开料','2012-6-8' union all
select 2,'王五','抽检','2012-6-8' union all
select 3,'王五','出货检验','2012-6-10' union all
select 4,'张三','送检','2012-6-9' union all
select 5,'王五','打包装','2012-6-9'
go

---------------------创建表以及插入数据，结束-----------------------------------
--开始select
select a.UID,a.username,a.Department,b.ProID,b.Item,
convert(char(10),b.CompleteDate,121)as CompleteDate
from a inner join b on a.username = b.username
inner join (select username,max(completeDate)as CompleteDate from b group by username)as c on b.username = c.username and c.CompleteDate = b.CompleteDate

--结果展示

/*
UID username Department ProID Item CompleteDate
----------- -------------------------------------------------- -------------------------------------------------- ----------- -------------------------------------------------- ------------
1 张三生产部 4 送检 2012-06-09
3 王五品质部 3 出货检验 2012-06-10

(2 行受影响)

*/

[其他解释]


;with t
as(
select
    u.uid,
    u.Username,
    u.Department,
    p.ProID,
    p.Item,
    p.CompleteDate
from Users u
inner join Products p
on u.Username=p.Username
)
select
    *
from
    t 
where
    t.CompleteDate=(select max(a.CompleteDate) from t a where a.username=t.uaername)

[其他解释]
可以这样写
[其他解释]
都有人回答了，结了吧。
[其他解释]

引用:

select * from Users a,Products b where a.Username=b.Username
and not eixsts(select 1 from Products where Username=b.Username and CompleteDate>b.CompleteDate)

这个不错！
[其他解释]
非常感谢各位的帮助，结贴了！

表连接SELECT语句

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