获得2数据集C＃的差异 [英] get the differences in 2 DataSets c#
问题描述
我写一个短算法具有比较两个数据集，以便在两者之间的差异可以进一步处理。
我tryed通过合并这两个数据集，并获得由此产生的变化到一个新的DataSet实现这一目标。
I am writing a short algorithm which has to compare two DataSets, so that the differences between both can be further processed. I tryed accomplishing this goal by merging these two DataSets and get the resulting changes into a new DataSet.
我的方法是这样的：
private DataSet ComputateDiff(DataSet newVersion, DataSet oldVersion)
{
DataSet diff = null;
oldVersion.Merge(newVersion);
bool foundChanges = oldVersion.HasChanges();
if (foundChanges)
{
diff = oldVersion.GetChanges();
}
return diff;
}
foundChanges的结果总是假的，即使两个数据集有不同的价值观在里面。
两个数据集有相同的strukture。它们由三个数据表它们是在数据库3 querys结果。
合并工作正常，没有问题。
The result of foundChanges is always false, even though the two DataSets have different values in it. Both DataSets have the same strukture. They consist of three DataTables which are the result of three querys in a Database. The merge works fine no problems with that.
我的问题是：
是否有任何合理的解释，为什么foundChanges变量始终是假的，如果不将的LINQ提供了这个问题的妥善解决还是我必须通过数据集进行迭代，以确定更改
My question is: Is there any reasonable explanation why the foundChanges variable is always false and if not would Linq provide a proper solution for this problem or do i have to determine the changes by iterating through the DataSets
下面是一些进一步的信息：
编程语言是我使用.NET Framework 4.0
提到我在Windows 8机器
中的数据开发来自数据库（MSSQL Server 2012的快递）
我的DataSet C＃
或数据表还没有得到任何PK的，据我所知。
Here are some further informations: The programming language is C# I am using .Net framework 4.0 I am developing on a Windows 8 Machine The Data as mentioned comes from a Database(MSSQL Server 2012 express) My DataSets or DataTables haven't got any PK's as far as i know.
在此先感谢
推荐答案
我认为这个问题是你不理解.NET数据集。的DataTable保留加载到每个值的原始副本。当一个值被改变时，数据表是能够检测的变化。同样，数据表跟踪已添加或删除的行。在 HasChanges（）功能只需通过数据表，并检查抓取，看看是否有过任何改变（改变值，新行，删除的行等）
I think the problem is that you don't understand .NET DataSets. A DataTable retains the "original" copy of each value loaded into it. When a value is changed, the DataTable is able to detect the change. Likewise, the DataTable keeps track of rows that have been added or deleted. The HasChanges() function simply crawls through the DataTables and checks to see if there's been any changes (changed value, new rows, deleted rows, etc.)
请参阅MSDN文档：结果
的 http://msdn.microsoft.com/en-us/library/system.data.dataset.haschanges.aspx
See the MSDN documentation:
http://msdn.microsoft.com/en-us/library/system.data.dataset.haschanges.aspx
比较两个数据集是棘手的，我不知道有任何内置函数来处理这（因为每一个程序员都会有自己的等价的定义）的。
Comparing two DataSets is tricky, and I'm not aware of any built-in function to handle this (since every programmer will have their own definition of "equivalence").
请参阅：
- 的如何比较数据表2的StackOverflow
- 的 CodeProject上使用LINQ 数据集比较
- How to compare 2 dataTables on StackOverflow
- Comparing DataSets using LINQ on CodeProject
代码下面将通过比较匹配行的值寻找基于一个键列添加/删除的行和修改行比较两个数据表（再次，基于该键）。 。这将是相当琐碎扩大这一比较数据集（由数据集之间的比较类似命名表）
The code below will compare two DataTables by looking for added/deleted rows based on a Key column and modified rows by comparing the values of matching rows (again, based on the key). It would be fairly trivial to expand this to compare DataSets (by comparing similarly-named tables between DataSets).
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
namespace DataSetComparison
{
class Program
{
static void Main( string[] args )
{
var l_table1 = new DataTable();
l_table1.Columns.Add( "Key", typeof( int ) );
l_table1.Columns.Add( "Name", typeof( string ) );
l_table1.Columns.Add( "Age", typeof( int ) );
var l_table2 = new DataTable();
l_table2.Columns.Add( "Key", typeof( int ) );
l_table2.Columns.Add( "Name", typeof( string ) );
l_table2.Columns.Add( "Age", typeof( int ) );
l_table1.Rows.Add( l_table1.NewRow() );
l_table1.Rows[l_table1.Rows.Count - 1]["Key"] = 0;
l_table1.Rows[l_table1.Rows.Count - 1]["Name"] = "Alfred Harisson";
l_table1.Rows[l_table1.Rows.Count - 1]["Age"] = 36;
l_table1.Rows.Add( l_table1.NewRow() );
l_table1.Rows[l_table1.Rows.Count - 1]["Key"] = 1;
l_table1.Rows[l_table1.Rows.Count - 1]["Name"] = "Matthew George";
l_table1.Rows[l_table1.Rows.Count - 1]["Age"] = 41;
l_table1.Rows.Add( l_table1.NewRow() );
l_table1.Rows[l_table1.Rows.Count - 1]["Key"] = 2;
l_table1.Rows[l_table1.Rows.Count - 1]["Name"] = "Franklin Henry";
l_table1.Rows[l_table1.Rows.Count - 1]["Age"] = 33;
l_table2.Rows.Add( l_table2.NewRow() );
l_table2.Rows[l_table2.Rows.Count - 1]["Key"] = 0;
l_table2.Rows[l_table2.Rows.Count - 1]["Name"] = "Alfred Harisson";
l_table2.Rows[l_table2.Rows.Count - 1]["Age"] = 36;
l_table2.Rows.Add( l_table2.NewRow() );
l_table2.Rows[l_table2.Rows.Count - 1]["Key"] = 1;
l_table2.Rows[l_table2.Rows.Count - 1]["Name"] = "Matthew George";
l_table2.Rows[l_table2.Rows.Count - 1]["Age"] = 42; // Record 1 "modified"
// Record 2 "deleted"
// Record 3 "added":
l_table2.Rows.Add( l_table2.NewRow() );
l_table2.Rows[l_table2.Rows.Count - 1]["Key"] = 3;
l_table2.Rows[l_table2.Rows.Count - 1]["Name"] = "Lester Kulick";
l_table2.Rows[l_table2.Rows.Count - 1]["Age"] = 33;
// Using table 1 as the control, find changes in table 2
// Find deleted rows:
var l_table2Keys = l_table2.Select().Select( ( r ) => (int) r["Key"] );
var l_deletedRows = l_table1.Select().Where( ( r ) => !l_table2Keys.Contains( (int) r["Key"] ) );
foreach ( var l_deletedRow in l_deletedRows )
Console.WriteLine( "Record " + l_deletedRow["Key"].ToString() + " was deleted from table 2." );
// Find added rows:
var l_table1Keys = l_table1.Select().Select( ( r ) => (int) r["Key"] );
var l_addedRows = l_table2.Select().Where( ( r ) => !l_table1Keys.Contains( (int) r["Key"] ) );
foreach ( var l_addedRow in l_addedRows )
Console.WriteLine( "Record " + l_addedRow["Key"].ToString() + " was added to table 2." );
// Find modified rows:
var l_modifiedRows = l_table2.Select()
.Join(
l_table1.Select(),
r => (int) r["Key"],
r => (int) r["Key"],
( r1, r2 ) => new
{
Row1 = r1,
Row2 = r2
} )
.Where(
values => !( values.Row1["Name"].Equals( values.Row2["Name"] ) &&
values.Row1["Age"].Equals( values.Row2["Age"] ) ) )
.Select( values => values.Row2 );
foreach ( var l_modifiedRow in l_modifiedRows )
Console.WriteLine( "Record " + l_modifiedRow["Key"].ToString() + " was modified in table 2." );
Console.WriteLine( "Press any key to quit..." );
Console.ReadKey( true );
}
}
}
控制台输出
Console output:
记录2，从表2结果
记录3删除添加到表2结果
记录1修改表2。
Record 2 was deleted from table 2.
Record 3 was added to table 2.
Record 1 was modified in table 2.
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