如何使用SQL Server中的XPath,XQuery以逗号分隔XML值

Question

我有一个XML列,其示例值为

<error>
  <errorno>BL04002055</errorno>
  <description>Smart Rule PROJECT_COUNTRYCODE_VAL Violated</description>
  <description2>Country Code is required</description2>
  <correction />
</error>
<error>
  <errorno>BL01001973</errorno>
  <description />
  <description2>Error While Saving the Project info</description2>
  <correction />
</error>
<error>
  <errorno>Unable to Create Custom Object</errorno>
  <description />
  <description2>Smart Rule PROJECT_COUNTRYCODE_VAL Violated: Country Code is required
Error While Saving the Project info</description2>
  <correction />
</error>

我想选择描述2值逗号分隔

select *
--, Response.value(''/error/description2/text()'', 'varchar(8000)') as parsedString
, Response.query('/error/description2/text()') as parsedString
 from #temp

这里有两个问题.

1. 我无法在上面的查询中运行值函数.
2. 使用查询,我获得没有空格或逗号连接的值.所以我需要在连接值上添加一些空格或逗号.

Answer 1

SQL Server没有实现xPath功能string-join,因此您需要采用两步流程,第一步是将所有术语提取到行使用nodes();

SELECT  n.value('.', 'VARCHAR(100)') AS parsedString
FROM    #temp AS t
        CROSS APPLY t.Response.nodes('/error/description2') r (n);

这为您提供了行的值:

parsedString
----------------------------------------------------------------------------
Country Code is required
Error While Saving the Project info
Smart Rule PROJECT_COUNTRYCODE_VAL Violated: Country Code is required
Error While Saving the Project

然后你可以添加你的分隔符并将它们连接起来,使用FOR XML PATH(''), TYPE,最后STUFF用来删除第一个分隔符:

SELECT  STUFF(( SELECT  ',' + n.value('.', 'VARCHAR(100)') AS parsedString
                FROM    #temp AS t
                        CROSS APPLY t.Response.nodes('/error/description2') r (n)
                FOR XML PATH(''), TYPE
            ).value('.', 'VARCHAR(MAX)'), 1, 1, '') AS ParsedString;

完整的工作示例

DECLARE @X XML = '<error>
  <errorno>BL04002055</errorno>
  <description>Smart Rule PROJECT_COUNTRYCODE_VAL Violated</description>
  <description2>Country Code is required</description2>
  <correction />
</error>
<error>
  <errorno>BL01001973</errorno>
  <description />
  <description2>Error While Saving the Project info</description2>
  <correction />
</error>
<error>
  <errorno>Unable to Create Custom Object</errorno>
  <description />
  <description2>Smart Rule PROJECT_COUNTRYCODE_VAL Violated: Country Code is required
Error While Saving the Project info</description2>
  <correction />
</error>';

SELECT  STUFF(( SELECT  ',' + n.value('.', 'VARCHAR(100)') AS parsedString
                FROM    (SELECT @X) AS t (Response)
                        CROSS APPLY t.Response.nodes('/error/description2') r (n)
                FOR XML PATH(''), TYPE
            ).value('.', 'VARCHAR(MAX)'), 1, 1, '') AS ParsedString;