当一个表的约束键具有很少的空值时，如何合并两个表的结果

Question

I am having two tables one is accomodation and one is hotelpaymententry what i want is to combine both the tables without repeating same enquiry_id. below are my tables and query what i tried and its result: Table Accomodation

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

Table 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

i tried join n union both for the result but inner join returns only common records and left & right join multiplies the records and return 5*3 records and union returns both tables records repeating the enquiry_id RH - 10/03/2014 - 3 means total 8 records. what i want is record from both tables but if enquiryid matches in both tables record appears once and if record is unique in its own table it appears a=in output table. help is badly needed. thanks to all for help in advance.

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

To get all records from accomodation and matching records from HotelPyamentEntry you can write as:

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

and to get records from both the tables you can do a FULL join as

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

one often struck when tables are not properly normalize.

Best solution would be to normalize your table with proper relationship .

It is not a case of Union or join or distinct .

See I will try something like this,

;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