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如何仅检测上载文件中的更改？

[英]How to detect only the changes in the uploaded file?

原文 2012-01-02 17:20:19 3 1 c#/ asp.net/ xml/ file/ crud

If i have an xml file (uploaded to my server), and i do some processing on it to get the data from it,then store those data in my database . 如果我有一个xml文件（已上传到服务器），并且对其进行了一些处理以从中获取数据，则将这些数据存储在数据库中。

If the user makes some changes (insert,update, delete),then upload the file again to my server . 如果用户进行了一些更改（插入，更新，删除），则将文件再次上传到我的服务器。 Is there any way to detect the changes (insert , update , delete)to update my database according to rather than just deleting all the data and inserting them again .especially ,there is some data depends on the the existing data(referential integrity)and if i delete all the data , the dependents will be deleted.(cascade delete)!! 有什么方法可以检测到更改（插入，更新，删除）以根据我的数据库进行更新，而不仅仅是删除所有数据并再次插入它们。特别是，有些数据取决于现有数据（参照完整性），并且如果我删除所有数据，则将删除依赖项。（级联删除）！

Note: 注意：

I store the file hash , so i know if there is some change is occurred since the last uploading. 我存储文件哈希，所以我知道自从上次上传以来是否发生了某些变化。

1 个解决方案

As Darin pointed out in his comment, this depends largely on the structure and content of both your XML file and your database. 正如Darin在他的评论中指出的那样，这在很大程度上取决于XML文件和数据库的结构和内容。

In principle currently you delete a set of rows of a certain number of tables and (re-)insert another set of rows afterwards. 原则上，当前您删除具有一定数量表的一组行，然后再（重新）插入另一组行。

If you only want to update your database, you could - for each table - first identify all rows you would currently delete (ie do a SELECT ... WHERE instead of a DELETE ... WHERE ), prepare a set of rows you would insert and compare these two sets (lets call them DELETE and INSERT ): 如果您只想更新数据库，则可以-对于每个表-首先确定当前要删除的所有行（即，执行SELECT ... WHERE而不是DELETE ... WHERE ），准备一组行插入并比较这两个集合（将它们称为DELETE和INSERT ）：

Rows that are only in the DELETE set have to be deleted from the database 必须从数据库中删除仅在DELETE集中的行
Rows that are only in the INSERT set have to be inserted 仅 插入INSERT集中的行
Rows that are in both the INSERT and DELETE set have to be updated. 行，也同时在插入和删除组必须进行更新。

But as mentioned, excatly how and in what order to perform these operations depends on your specific data structures. 但是如前所述，执行这些操作的方式和顺序完全取决于您的特定数据结构。 Eg if you have dependencies between tables (ie parent-child relationships), the delete operation on a parent entity has also to take care of the childs (possibly using a ON DELETE CASCADE clause in your foreign key definition). 例如，如果您在表之间具有依赖性（即，父子关系），则对父实体的删除操作还必须照顾孩子（可能在外键定义中使用ON DELETE CASCADE子句）。 In this case you should also process parent tables befor their child tables. 在这种情况下，您还应该在其子表之前处理父表。