连接来自同一列 Oracle 11G 的大量文本数据

Question

我使用的是企业版 11.2.0.4.0。我想将每个学生的评论从 table 连接成一个巨大的评论，然后将其输出（假脱机）到一个文件中。

我的 table TEACHER_COMMENTS 有列：

SID  INT
COMMENTS VARCHAR2(4000)

数据如下所示：

SID   COMMENTS
1    It has truly been a pleasure getting to know your child this quarter. our child has made great progress across the curriculum since the beginning of the school year.
1    Your child has done a very nice job this quarter, taking pride in her work and completing assignments with quality in mind.. Your child has made very good academic and/or social progress this quarter.

我想将同一位学生的评论合并为一个大评论。

这是我的代码：

SET ECHO OFF NEWP 0 SPA 0 PAGES 0 FEED OFF HEAD OFF TRIMS ON
set underline off
set pages 0
set lines 1500
set feedback off
set autop off
set term off
set ver off
set timing off
set time off

spool E:\Test\Comments.csv

SELECT wm_concat(COMMENTS) FROM  TEACHER_COMMENTS t GROUP BY SID;

spool off;

exit;

这只输出一行评论，而不是整个大评论。

我也试过使用LIST_AGG

SELECT LISTAGG(COMMENT, ' ') WITHIN GROUP (ORDER BY COMMENT) AS All_Comments
FROM  TEACHER_COMMENTS t
GROUP BY SID

这会引发错误：

ORA-01489: result of string concatenation is too long

我该怎么做？请帮忙。

Answer 1

既然你有 11.2，你应该可以使用 listagg。

SELECT LISTAGG(comments, ',') WITHIN GROUP (ORDER BY sid) AS BIGCOMMENT
FROM   teacher_comments
GROUP BY sid;

我不记得 listagg returns 是否是 clob，但如果是，我会在使用上面的 SQL 之前听从 Jon Heller 的建议。不过，您肯定想停止使用 wm_concat。

Answer 2

ORA-01489: result of string concatenation is too long

LISTAGG returns VARCHAR2 (or RAW) 因此限制为 4000 字节。 SQL*Plus 默认情况下有 linesize 80.

一种可能的解决方案是使用 XMLAGG 并将 LONG 设置为较高的值。让我们看看它是如何工作的 -

SQL> SET LONG 2000000000
SQL> WITH DATA AS(
  2  SELECT 1 SID, 'It has truly been A pleasure getting TO know your CHILD
  3  this quarter. our CHILD has made great progress across THE curriculum
  4  since THE beginning OF THE school YEAR.' comments FROM dual UNION ALL
  5  SELECT 1, 'Your child has done a very nice job this quarter, taking pride
  6  in her work and completing assignments with quality in mind.. Your child
  7  has made very good academic and/or social progress this quarter.' FROM dual
  8  )
  9  SELECT rtrim(xmlagg(XMLELEMENT(e,comments,',').EXTRACT('//text()')
 10  ORDER BY sid).GetClobVal(),',') as long_comments
 11  FROM DATA
 12  /

LONG_COMMENTS
--------------------------------------------------------------------------------
It has truly been A pleasure getting TO know your CHILD
this quarter. our CHILD has made great progress across THE curriculum
since THE beginning OF THE school YEAR.,Your child has done a very nice job this
 quarter, taking pride
in her work and completing assignments with quality in mind.. Your child
has made very good academic and/or social progress this quarter.


SQL>

连接来自同一列 Oracle 11G 的大量文本数据

Concatenating huge amount of text data from the same column Oracle 11G

sql

oracle

oracle11g