oracle 从联合选择中选择计数答案

【问题标题】：oracle select count from union selectionoracle 从联合选择中选择计数
【发布时间】：2018-05-07 13:54:13
【问题描述】：

我只需要得到总 cmets。所以我的查询需要选择和计数。这是我的sql。我对 total_cmets

有疑问

SELECT customid, 
       dt, 
       customer_name, 
       e_mail, 
       phone, 
       TYPE, 
       message, 
       crm_status_id,
       total_comments
FROM   (SELECT f.ROWID                                AS customid, 
               f.dt                                   AS d, 
               To_char(f.dt, 'YYYY-MM-DD HH24:MI:SS') AS dt, 
               f.first_name 
               || ' ' 
               || f.middle_name 
               || ' ' 
               || f.last_name                         AS customer_name, 
               f.e_mail, 
               f.phone, 
               Decode(f.feedback_type, 'CALLBACK', 'CALLBACK', 
                                       'FEEDBACK')    AS TYPE, 
               f.feedback_message                     AS message, 
               f.crm_status_id                        AS crm_status_id,
               (SELECT COUNT(*) FROM CRM_FEEDBACK_COMMENTS WHERE CRM_FEEDBACK_COMMENTS.FEEDBACK_ROW_ID = f.customid) as total_comments
        FROM   crm_feedback f 
        UNION ALL 
        SELECT g.ROWID                                       AS customid, 
               create_date                                   AS d, 
               To_char(create_date, 'YYYY-MM-DD HH24:MI:SS') AS dt, 
               c.customer_name1                              AS customer_name, 
               p.email, 
               p.phone, 
               'MOBILSHOBE FEEDBACK'                         AS TYPE, 
               g.message_body                                AS message, 
               g.crm_status_id                               AS crm_status_id,
               (SELECT COUNT(*) FROM CRM_FEEDBACK_COMMENTS WHERE FEEDBACK_COMMENTS.FEEDBACK_ROW_ID = g.customid) as total_comments             
        FROM   feedback g 
               inner join sttm_customer@fcc_dblink c 
                       ON c.customer_no = g.customer_no 
               inner join pg2_customer@fcc_dblink p 
                       ON p.cif = g.customer_no)

我收到此错误：[Err] ORA-00904: "F"."CUSTOMID": invalid identifier

【问题讨论】：

也许使用 f.rowID 而不是 f.customID？执行该行时，customID 别名尚不存在。就我个人而言，我会加入一个包含 row_ID 计数的派生表，所以我对所有 row_ID 进行一次计算，而不是每个行 ID 计算一次。 MySQL 可能允许您引用先前在同一记录上使用的别名；我不相信 oracle 会这样做。

标签： sql oracle union

【解决方案1】：

您的表CRM_FEEDBACK_COMMENTS 使用CRM_FEEDBACK.rowid 作为外键。这是一个糟糕的设计，有几个原因。

它不是真正的外键，因为我们无法构建实际的外键引用父 ROWID 的约束。
ROWID 不是保证值：行可以移动（尽管很少）在这种情况下，您的子记录是孤立的。
正如您所发现的那样，编写连接是一件令人头疼的事情。

ORA-00904：“F”。“CUSTOMID”：标识符无效

您收到此错误消息是因为我们无法将列别名传递给标量游标。要解决您最初的问题，您需要将CRM_FEEDBACK.rowid 带入与CRM_FEEDBACK_COMMENTS.FEEDBACK_ROW_ID 相同的范围内。您可以使用内联视图（即 FROM 子句中的子查询）来做到这一点：

   SELECT g.ROWID                                       AS customid, 
           create_date                                   AS d, 
           To_char(create_date, 'YYYY-MM-DD HH24:MI:SS') AS dt, 
           c.customer_name1                              AS customer_name, 
           p.email, 
           p.phone, 
           'MOBILSHOBE FEEDBACK'                         AS TYPE, 
           g.message_body                                AS message, 
           g.crm_status_id                               AS crm_status_id,
    FROM   feedback g 
           left outer join 
               (SELECT FEEDBACK_ROW_ID, COUNT(*) as total_comments  
                FROM CRM_FEEDBACK_COMMENTS 
                group by FEEDBACK_ROW_ID) comm
                on chartorowid(comm.FEEDBACK_ROW_ID) = g.ROWID       
           inner join sttm_customer@fcc_dblink c 
                   ON c.customer_no = g.customer_no 
           inner join pg2_customer@fcc_dblink p 
                   ON p.cif = g.customer_no)

【讨论】：