当一个表的约束键具有很少的空值时，如何组合两个表的结果

Question

我有两个表，一个是住宿，一个是hotelpaymententry我想要的是将两个表组合而不重复相同的enquiry_id。下面是我的表格，并查询我尝试的内容及其结果：  表住宿

Enquiry_Id             Checkin      CheckOut    hotelname              Amount
RH - 26/02/2014 - 10 2014-03-18 2014-03-19  Spice Routes Houseboats     15500
RH - 04/03/2014 - 1  2014-03-19 2014-03-20  Spice Routes Houseboats     9000
RH - 04/03/2014 - 2  2014-03-17 2014-03-18  Spice Routes Houseboats     24000
RH - 05/03/2014 - 6  2014-04-04 2014-04-05  Spice Routes Houseboats     9000
RH - 10/03/2014 - 3  2014-06-17 2014-06-18  Spice Routes Houseboats     33000

表HotelPyamentEntry

![enter image description here][1]

 Hotel                   EnquiryId         Checkin    CheckOUt   Totalamount  paynow  dateofpayment 

Spice Routes Houseboats     NULL             NULL       NULL        NULL        5000    2014-12-09
Spice Routes Houseboats     NULL             NULL       NULL        NULL        6000    2014-12-10
Spice Routes Houseboats RH - 10/03/2014 - 3  2014-06-17 2014-06-18  33000      15000    2014-12-08

我尝试加入n union以获得结果，但内部联接仅返回常见记录并且左和右右连接乘以记录并返回5 * 3记录，并且union返回两个表记录重复enquiry_id RH - 10/03/2014 - 3表示总共8条记录。我想要的是来自两个表的记录，但如果两个表中的enquiryid匹配记录出现一次，如果记录在其自己的表中是唯一的，则在输出表中出现a =。迫切需要帮助。感谢所有人提前帮助。

Answer 1

  select Enquiry_Id,Checkin,CheckOut,hotelname,Amount from Table Accomodation
    union //union doesn't take redundant data
    select Enquiry_Id,Checkin,CheckOut,hotelname,Amount from Table HotelPyamentEntry

Answer 2

要获取accomodation的所有记录以及来自HotelPyamentEntry的匹配记录，您可以写为：

SELECT A.Enquiry_Id  
,A.Checkin 
,A.CheckOut 
,A.hotelname 
,A.Amount
,H.paynow
,H.dateofpayment
FROM @Accomodation A 
outer apply
(
SELECT hotel 
,Enquiry_Id  
,Checkin 
,CheckOut 
,Totalamount 
,paynow 
,dateofpayment 
FROM @HotelPyamentEntry HP
WHERE HP.Enquiry_Id = A.Enquiry_Id )AS H

要从两个表中获取记录，您可以FULL join作为

SELECT DISTINCT ISNULL(A.Enquiry_Id  ,H.Enquiry_Id)AS Enquiry_Id
,ISNULL(A.Checkin ,H.Checkin)AS Checkin
,ISNULL(A.CheckOut ,H.CheckOut)AS CheckOut
,ISNULL(A.hotelname ,H.hotel)AS hotelname
,ISNULL(A.Amount,H.Totalamount)AS Amount
,H.paynow
,H.dateofpayment
FROM @Accomodation A
FULL JOIN @HotelPyamentEntry H ON A.Enquiry_Id= H.Enquiry_Id

DEMO

Answer 3

  

当表格没有正确规范化时，经常会发生这种情况。

     

最好的解决方案是正确地规范你的桌子   关系。

     

这不是联盟或加入或不同的情况。

看，我会尝试这样的事，

;With CTE As
(
SELECT  A.Enquiry_Id  AS Enquiry_Id
,A.Checkin AS Checkin
,A.CheckOut CheckOut
,A.hotelname  hotelname
,Amount AS Amount
,0 paynow
,0 dateofpayment
FROM @Accomodation A
UNION all
SELECT H.Enquiry_Id 
,H.Checkin
,H.CheckOut
,H.hotelname
,H.Totalamount
,H.paynow
,H.dateofpayment


FROM @HotelPyamentEntry H 
)
-- analyze this and check which rows you want and which which rows tyou want to eliminate and why.
--then accordsingly put ranking function with partition by and order

select * 
ROW_NUMBER(partition by order by )rownum 
from CTE