Question

我需要比较两个表（表A作为生产数据，B作为旧数据）之间的电子邮件记录（通过电子邮件地址）来查找差异并在列中显示结果，例如＆＃34; New＆＃34;，＆＃34;删除＆＃34;等等。

如果表A中存在，而不是表B中，则应标记＆＃34;新＆＃34;

否则，如果表B中存在，而不是表A中，则应标记＆＃34;删除＆＃34;

如果出现在两个表中，则应标记＆＃34;维护＆＃34;

我想要那样的结果

DisplayName     LastName    Diremail    Result
==============================================
XXX             XXX         a@a.com     New
ABC             ABC         1@a.com     Delete
DDD             DDD         2@a.com     Maintain

我的代码如下：

SELECT  b.DisplayName,
        b.LastName,
        b.diremail,        
        Result = CASE WHEN a.DirEmail IS NULL THEN 'New'   
        when b.DirEmail IS null then 'delete'     
                    else 'Maintain'
                END
FROM    vHRIS_StaffDB b    
        LEFT JOIN HRIS_DL_Lists a
            ON a.DirEmail = b.DirEmail
WHERE (
a.DirEmail IS NULL
OR      a.DisplayName != b.DisplayName
)

但数据不正确，因为代码不返回记录，应该＆＃34;删除＆＃34; （见表b，而不是表a）

请指教。谢谢。

Answer 1

听起来你需要完全加入而不是左连接。试试这个：

SELECT  coalesce(b.DisplayName, a.DisplayName) DisplayName,
        coalesce(b.LastName, a.LastName) LastName,
        coalesce(b.diremail, a.diremail) diremail,
        Result = CASE WHEN a.DirEmail IS NULL THEN 'New'   
        when b.DirEmail IS null then 'delete'     
                    else 'Maintain'
                END
FROM    vHRIS_StaffDB b    
        FULL JOIN HRIS_DL_Lists a
            ON a.DirEmail = b.DirEmail
WHERE (
a.DirEmail IS NULL
OR      a.DisplayName != b.DisplayName
)

SQL找到两个表之间的区别

1 个答案: