Question

我在SQL Server中有一个查询返回一个Reports列表，它必须返回一个表示位置的字符串，或者一个表示它引用的存储的字符串。

问题是我的查询只返回引用商店ID的报表，而不是返回所有报表和相关位置信息。我确信它是一个愚蠢的语法问题，但我暂时还没有完成数据库工作，似乎无法解决它。我已经尝试了几种不同的方法来实现这一点，但它只是拒绝。

SELECT rep.rep_id                                                                   AS "RepId",
       Isnull(rep.rep_status, 'C')                                                  AS "RepStatus",
       Isnull(( loc.location_street + ' ' + loc.location_city ), store.Description) AS "Location",
       rep.date_reported                                                            AS "DateReported",
       rep.reported_by                                                              AS "ReportedBy"
FROM   Report rep
       JOIN Report_Location reploc
         ON reploc.rep_id = rep.rep_id
       JOIN Location loc
         ON loc.location_id = reploc.location_id
       LEFT JOIN Store store
              ON store.StoreID = loc.store_id;

我尝试删除左连接，只添加一个loc.store_id = store.StoreID或loc.store_id IS NULL。都没有奏效。在此先感谢您的帮助。

Answer 1

您需要使用LEFT OUTER JOIN代替Inner Join

SELECT rep.rep_id                                                                   AS "RepId",
       Isnull(rep.rep_status, 'C')                                                  AS "RepStatus",
       Isnull(( loc.location_street + ' ' + loc.location_city ), store.Description) AS "Location",
       rep.date_reported                                                            AS "DateReported",
       rep.reported_by                                                              AS "ReportedBy"
FROM   Report rep
       LEFT JOIN Report_Location reploc
              ON reploc.rep_id = rep.rep_id
       LEFT JOIN Location loc
              ON loc.location_id = reploc.location_id
       LEFT JOIN Store store
              ON store.StoreID = loc.store_id;

Answer 2

使用左外连接实现：

SELECT        rep.rep_id AS RepId, ISNULL(rep.rep_status, 'C') AS RepStatus, ISNULL(loc.location_street + ' ' + loc.location_city, store.Description) AS Location, 
                         rep.date_reported AS DateReported, rep.reported_by AS ReportedBy
FROM            Report AS rep LEFT OUTER JOIN
                         Report_Location AS reploc ON reploc.rep_id = rep.rep_id LEFT OUTER JOIN
                         Location AS loc ON loc.location_id = reploc.location_id LEFT OUTER JOIN
                         Store AS store ON store.StoreID = loc.store_id

SQL Server查询帮助

2 个答案: