SQL Server查询:使用JOIN包含NULL值
发布时间:2020-12-12 07:02:16 所属栏目:MsSql教程 来源:网络整理
导读:我需要有关以下SQL Server查询的帮助,其中a.TAProfileID和c.CountryCode列在数据库中具有“NULL”值. 我希望我的JOIN语句返回存在的“NULL”值. SELECT a.ReservationStayID AS 'Reservation Id',a.PMSConfirmationNumber as 'PMS No',a.CreatedOn AS 'Date C
我需要有关以下SQL Server查询的帮助,其中a.TAProfileID和c.CountryCode列在数据库中具有“NULL”值.
我希望我的JOIN语句返回存在的“NULL”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 解决方法要返回或生成NULL值,您必须使用LEFT JOIN.所以,你的查询应该是这样的: SELECT a.ReservationStayID AS 'Reservation Id',a.PMSConfirmationNumber AS 'PMS No',c.NAME AS 'Travel Agency',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 (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |