Question

我已经错误地发布了同样的帖子。因此，要求纠正相同的问题。在此查询中是否可以避免使用UNION？任何人都可以帮助这个查询吗？提前致谢

SELECT A.M_TITLE, 
       A.M_NUMBER, 
       B.M_NAME, 
       B.M_DESCRIPTION, 
       A.FORM_TYPE, 
       B.SUBMISSION_DATE, 
       B.CREATON_DATE, 
       A.R_OBJECT_ID AS FORM_ID,
       B.R_OBJECT_ID AS FORMDATA_ID, 
       ''            AS ATTACHMENTS 
FROM M_FORM A, 
     M_FORMDATA B 
WHERE A.M_NUMBER = B.M_NUMBER 
AND ANY B.ATTACHMENTS IN 
    (SELECT ATTACHMENTS FROM M_FORMDATA C WHERE B.M_NUMBER = C.M_NUMBER) 
AND ACTION_ID = 'XXXX' 
AND SUBMISSION_DATE >= DATE('XXXX') 
AND SUBMISSION_DATE <= DATE('XXXX') 

UNION 

SELECT A.M_TITLE, 
       A.M_NUMBER, 
       B.M_NAME, 
       B.M_DESCRIPTION, 
       A.FORM_TYPE, 
       B.SUBMISSION_DATE, 
       B.CREATION_DATE, 
       A.R_OBJECT_ID AS FORM_ID,
       B.R_OBJECT_ID AS FORMDATA_ID, 
       'null'        AS ATTACHMENTS 
 FROM M_FORM A, 
      M_FORMDATA 
 WHERE A.M_NUMBER = B.M_NUMBER 
 AND NOT ANY B.ATTACHMENTS IN 
      (SELECT ATTACHMENTS FROM M_FORMDATA C WHERE B.M_NUMBER = C.M_NUMBER) 
 AND ACTION_ID= 'XXXX' 
 AND SUBMISSION_DATE >= DATE('XXXX') 
 AND SUBMISSION_DATE <= DATE('XXXX')

Answer 1

如果我正确理解了查询，唯一的区别在于如何定义ATTACHMENTS。你可以做出有条件的：

SELECT A.M_TITLE, 
       A.M_NUMBER, 
       B.M_NAME, 
       B.M_DESCRIPTION, 
       A.FORM_TYPE, 
       B.SUBMISSION_DATE, 
       B.CREATON_DATE, 
       A.R_OBJECT_ID AS FORM_ID,
       B.R_OBJECT_ID AS FORMDATA_ID, 
       (case when B.ATTACHMENTS IN (SELECT ATTACHMENTS FROM M_FORMDATA C WHERE B.M_NUMBER = C.M_NUMBER) 
             then ''
        end) AS ATTACHMENTS 
FROM M_FORM A join
     M_FORMDATA B 
     on A.M_NUMBER = B.M_NUMBER 
WHERE ACTION_ID = 'XXXX' AND
      SUBMISSION_DATE >= DATE('XXXX') AND SUBMISSION_DATE <= DATE('XXXX') ;

我还更改了join语法以使用显式连接（使用on子句）。

不使用UNION语法简化oracle查询

1 个答案: