Order by 子句不适用于此查询答案

【问题标题】：Order by clause is not working with this queryOrder by 子句不适用于此查询
【发布时间】：2016-01-12 05:32:04
【问题描述】：

CREATE TABLE `cc_comment_master` (
  `ID` int(11) DEFAULT NULL,
  `DRAFT_SALESDOC_HEADER_ID` int(11) DEFAULT NULL,
  `PRODUCT_ID` int(11) DEFAULT NULL,
  `PRODUCT_NUMBER` varchar(50) DEFAULT NULL,
  `COMMENT_DESC` varchar(100) DEFAULT NULL,
  `COMMENT_BY` varchar(50) DEFAULT NULL,
  `COMMENT_ON` datetime DEFAULT NULL,
  `MODIFIED_BY` varchar(100) DEFAULT NULL,
  `MODIFIED_ON` datetime DEFAULT NULL,
  `CREATED_BY` varchar(100) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;


insert  into `cc_comment_master`(`ID`,`DRAFT_SALESDOC_HEADER_ID`,`PRODUCT_ID`,`PRODUCT_NUMBER`,`COMMENT_DESC`,`COMMENT_BY`,`COMMENT_ON`,`MODIFIED_BY`,`MODIFIED_ON`,`CREATED_BY`) 
values (1,1,1,'abc','first','test','2016-01-12 10:43:48','test',NULL,'test'),(2,2,2,'def','second','test','2016-01-12 10:43:53','test',NULL,'test'),(3,3,3,'xyz','third','test','2016-01-12 10:43:56','test',NULL,'test'),(4,4,4,'pqr','four','test','2016-01-12 10:44:33','test',NULL,'test');

查询：

declare @comments  varchar(max)
set @comments = ''

Select 
    @comments = @comments +''+ COMMENT_DESC+'-COMMENT_SEPERATOR-' 
from 
    CC_COMMENT_MASTER c 
where 
    c.DRAFT_SALESDOC_HEADER_ID = 1
    and PRODUCT_NUMBER = 'abc'
order by 
    c.COMMENT_ON  desc   --order by not working 

select @comments;

我想选择附加在一个字符串中的所有 COMMENT_DESC，按 COMMENT_ON 降序排列。

如果没有 order by 子句，我将在一个字符串中按 asc 顺序获取所有 COMMENT_DESC。当我尝试通过 COMMENT_ON desc 订购时，它不起作用。

输出：

first-COMMENT_SEPERATOR-

预期输出：

first-COMMENT_SEPERATOR-second-COMMENT_SEPERATOR-third--COMMENT_SEPERATOR-

错误：

The ORDER BY clause is invalid in views, inline functions, derived tables, subqueries, and common table expressions, unless TOP or FOR XML is also specified.

【问题讨论】：

请注明您使用的实际RDBMS。
您可以在ORDER BY 子句中使用ID 代替COMMENT_ON。它将提供所需的输出。

标签： mysql sql sql-order-by

【解决方案1】：

试试这个

declare @comments  varchar(max)
set @comments = ''

Select 
    @comments =  @comments +''+ COMMENT_DESC+'-COMMENT_SEPERATOR-' 
from 
    (select top 100 percent * from CC_COMMENT_MASTER c  order by COMMENT_ON  desc) as t 

select @comments;

【讨论】：

【解决方案2】：

他们将不会在 where 子句中为该条件订购多条记录。只要去掉条件，我想它会起作用的

declare @comments varchar(max) set @comments = '' Select @comments = @comments +''+ COMMENT_DESC+'-COMMENT_SEPERATOR-' from CC_COMMENT_MASTER c order by c.COMMENT_ON desc

并删除该 desc 它将向后输出。

【讨论】：

【解决方案3】：

以下查询对我有用。

 DECLARE @comments nvarchar(max);
 SET @comments=''; 

 SELECT @comments= @comments +''+ TEMP.COMMENT_DESC +'COMMENT_SEPERATOR' 
 FROM
 (SELECT *, ROW_NUMBER() OVER (ORDER BY c.COMMENT_ON) AS RowNum FROM CC_COMMENT_MASTER   c  
 WHERE c.DRAFT_SALESDOC_HEADER_ID=1 AND c.PRODUCT_NUMBER='abc' ) AS TEMP
 ORDER BY TEMP.RowNum;

  SELECT @comments;

【讨论】：