Question

我正在使用SQL Server Compact Edition作为我的应用程序的数据库。

我有一个字符串

C:\wwsoftware\Application Server\3.0.000\3.0.001\IAS 3.0 P01.zip

我需要从该字符串中获取IAS 3.0 P01.zip值。

我可以使用SQL Server来完成此任务，但无法在SQL Server CE中执行此任务。

请帮助我。

提前致谢。

Answer 1

cordova plugin rm cordova-plugin-console

Answer 2

3N1GM4 已经要求您澄清在SQL Server中成功使用的方法，其次，您没有分享该信息，也没有详细说明为什么不起作用。

我将在这里说出你正在使用REVERSE（）函数来反转字符串和CHARINDEX（）然后找到第一个反斜杠。

与SQL Server SQL Server Compact 4.0 does not have a REVERSE() function不同，这使得提取文件名的最终反斜杠变得非常困难。

SQL Server Compact中缺少存储过程意味着它是另一种无法使用的途径。

ErikEJ 提供了一个很好的替代方案，即使用.NET Framework来完成繁重的工作。如果您具有访问SQL Server Compact数据库的.NET应用程序代码，那么您可以在.NET代码本身中提取文件名。我会建议ErikEJ的方法是最好的。

如果你坚持留在SQL Server Compact领域，那么纯粹在SQL中的唯一选择将包括粗糙的hacks或“臭”代码。

我一般不提倡或支持这种方法，但是如果你想要了解如何解决这个问题，那么就会出现以下SQL语句 - 它会尝试识别反斜杠在第一个字母，下一个字母等位置的位置，然后使用MAX（）函数找到最后一个反斜杠的位置。然后使用它，然后使用SUBSTRING（）函数提取文件名。

-- I do not recommend this crude approach! 
SELECT SUBSTRING(PATH, LAST_BACKSLASH + 1, LEN(PATH)) 
FROM ( 
SELECT MAX(CHARINDEX('\', PATH_QUERY.PATH, NUMBER)) as LAST_BACKSLASH, PATH_QUERY.PATH as PATH 
FROM ( 
SELECT 0 as NUMBER UNION ALL 
SELECT 1 as NUMBER UNION ALL 
SELECT 2 as NUMBER UNION ALL 
SELECT 3 as NUMBER UNION ALL 
SELECT 4 as NUMBER UNION ALL 
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SELECT 86 as NUMBER UNION ALL 
SELECT 87 as NUMBER UNION ALL 
SELECT 88 as NUMBER UNION ALL 
SELECT 89 as NUMBER           -- Best to extend this count to a larger number, like 300+ 
) AS NUMBER_LIST 
CROSS JOIN (SELECT 'C:\wwsoftware\Application Server\3.0.000\3.0.001\IAS 3.0 P01.zip' as PATH) as PATH_QUERY 
GROUP BY PATH_QUERY.PATH 
) as X

它很粗糙，因为它是一种强力方法，它需要适应允许的最大路径长度（由您的应用程序和the maximum path length of the OS）。

鉴于SQL Server Compact是一个嵌入式数据库（而不是客户端服务器数据库），因此没有理由不像ErikEJ建议的那样在应用程序代码中进行某些数据处理。这并不是说你减少了通过网络传输的结果集的大小。

从SQL Server CE中的字符串中获取最后一个索引值

2 个答案: