Question

我需要有关以下SQL Server查询的帮助，其中a.TAProfileID和c.CountryCode列具有＆＃34; NULL＆＃34;数据库中的值。

我希望我的JOIN语句返回＆＃34; NULL＆＃34;它们存在的价值。

SELECT 
a.ReservationStayID AS 'Reservation Id',
a.PMSConfirmationNumber as 'PMS No',
a.CreatedOn AS 'Date Created',
a.ArrivalDate AS 'Date of Arrival',
a.DepartureDate AS 'Date of Departure',
a.TAProfileID AS 'TA Id',
a.StatusCode AS 'Status',
b.PropertyCode AS 'Hotel',
c.Name AS 'Travel Agency',
c.CountryCode AS 'Market Code',
d.CountryName AS 'Mkt'

FROM ReservationStay a

inner JOIN GuestStaySummary b ON a.ReservationStayID = b.ReservationStayID
inner JOIN TravelAgency c ON a.TAProfileID = c.TravelAgencyID
inner JOIN Market d ON c.CountryCode = d.CountryCode

Answer 1

要返回或生成NULL个值，您必须使用LEFT JOIN s。

因此，您的查询应该是：

SELECT 
     a.ReservationStayID AS 'Reservation Id'
    ,a.PMSConfirmationNumber AS 'PMS No'
    ,a.CreatedOn AS 'Date Created'
    ,a.ArrivalDate AS 'Date of Arrival'
    ,a.DepartureDate AS 'Date of Departure'
    ,a.TAProfileID AS 'TA Id'
    ,a.StatusCode AS 'Status'
    ,b.PropertyCode AS 'Hotel'
    ,c.NAME AS 'Travel Agency'
    ,c.CountryCode AS 'Market Code'
    ,d.CountryName AS 'Mkt'
FROM ReservationStay a
    INNER JOIN GuestStaySummary b ON a.ReservationStayID = b.ReservationStayID
    LEFT JOIN TravelAgency c ON a.TAProfileID = c.TravelAgencyID
    LEFT JOIN Market d ON c.CountryCode = d.CountryCode

SQL Server查询：使用JOIN包含NULL值

1 个答案: