可能为空值的TSQL连接

我有一个小的存储过程，它正在拉入记录。表中当前有2条记录。其中一个具有

a.[manageraproval]

的值，而另一个没有。由于连接，如果列没有值，则不会显示整个记录，而只是一个空值

无论其连接的列是否有值，仍然显示数据的好方法是什么

SELECT A.[id],
       A.[empID],
       A.[firstName],
       A.[lastName],
       A.[emailAddress],
       B.[FirstName] + ' ' +B.[LastName] + ' (' +B.[ntid]+ ')' as managerApproval
FROM   tuitionSubmissions as A
JOIN empTable AS B
ON B.[empID] = A.[managerApproval]
FOR    XML PATH ('data'), TYPE, ELEMENTS, ROOT ('root');

---

使用

左外部联接

-如果值存在于第二个表中，它将联接该值上的表，否则它将返回

NULL

，用于从第二个表中选择

中的任何值

SELECT A.[id],
       A.[empID],
       A.[firstName],
       A.[lastName],
       A.[emailAddress],
       B.[FirstName] + ' ' +B.[LastName] + ' (' +B.[ntid]+ ')' as managerApproval
FROM   tuitionSubmissions as A
LEFT OUTER JOIN empTable AS B
ON B.[empID] = A.[managerApproval]
FOR    XML PATH ('data'), TYPE, ELEMENTS, ROOT ('root');

对于这些记录，
managerApproval
将为
NULL
似乎您需要左连接：

  SELECT A.[id],
       A.[empID],
       A.[firstName],
       A.[lastName],
       A.[emailAddress],
       B.[FirstName] + ' ' +B.[LastName] + ' (' +B.[ntid]+ ')' as managerApproval
    FROM   tuitionSubmissions as A
    Left JOIN empTable AS B
    ON B.[empID] = A.[managerApproval]
   FOR    XML PATH ('data'), TYPE, ELEMENTS, ROOT ('root');

将您的
Join
更改为
Left Join