问题与Oracle SQL

Question

谁能告诉我，为什么我收到以下错误：

“ORA-00904： ”MESSAGE_BODY“：无效识别符”

当我运行下面的查询对Oracle数据库？

SELECT COMMERCIAL_ID, MIN(dbms_lob.substr(MESSAGE_BODY, 3999, 1)) AS MESSAGE_BODY
FROM DWH_F_MP_MESSAGE_VW
GROUP BY COMMERCIAL_ID;

MESSAGE_BODY字段是CLOB

Answer 1

看来，DWH_F_MP_MESSAGE_VW不包含名为MESSAGE_BODY列。

这里有一个演示：

SQL> create table dwh_f_mp_message_vw (commercial_id number, message_body clob);

Table created.

SQL> insert into dwh_f_mp_message_vw values (1, 'Littlefoot');

1 row created.

SQL> select commercial_id, min(dbms_lob.substr(message_body, 3999, 1))
  2  from dwh_f_mp_message_vw
  3  group by commercial_id;

COMMERCIAL_ID
-------------
MIN(DBMS_LOB.SUBSTR(MESSAGE_BODY,3999,1))
--------------------------------------------------------------------------------
            1
Littlefoot


SQL> select commercial_id, min(dbms_lob.substr(message_bodyyyyyy, 3999, 1))
  2  from dwh_f_mp_message_vw
  3  group by commercial_id;
select commercial_id, min(dbms_lob.substr(message_bodyyyyyy, 3999, 1))
                                          *
ERROR at line 1:
ORA-00904: "MESSAGE_BODYYYYYY": invalid identifier


SQL>

我建议你运行以下命令：

SQL> desc dwh_f_mp_message_vw
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------
 COMMERCIAL_ID                                      NUMBER
 MESSAGE_BODY                                       CLOB

并发布结果回到这里（除非你看着办吧;在这种情况下，请解释一下什么地方出了错）。一种可能的罪魁祸首是下双引号创建的列，例如

SQL> drop table dwh_f_mp_message_vw;

Table dropped.

SQL> create table dwh_f_mp_message_vw (commercial_id number, "message_body" clob);

Table created.

SQL> insert into dwh_f_mp_message_vw (commercial_id, message_body) values (1, 'Littlefoot');
insert into dwh_f_mp_message_vw (commercial_id, message_body) values (1, 'Littlefoot')
                                                *
ERROR at line 1:
ORA-00904: "MESSAGE_BODY": invalid identifier


SQL> insert into dwh_f_mp_message_vw (commercial_id, "message_body") values (1, 'Littlefoot');

1 row created.

SQL> desc dwh_f_mp_message_vw
 Name                                      Null?    Type
 ----------------------------------------- -------- -------------------
 COMMERCIAL_ID                                      NUMBER
 message_body                                       CLOB

SQL>

如果是这样的话，摆脱双引号的。