2个数据表之间的差异 [英] difference between 2 datatables

问题描述

我有两个数据表。 DataTable dtRequired和DataTable dtResult。

我想输出一个datatable，它包含dtResponse中不存在但在dtRequired中找到的行。

方法1
我们一直在使用以下url指定的算法 http://weblogs.sqlteam.com/davidm/archive/2004/01/19/739.aspx 。
这个算法被认为是我们剖析中较慢的算法之一。

方法2
所以，我试图用下面描述的东西替换上述算法。
dtRequired在我使用的列上索引到查找行。

  if（dtResult.Rows.Count> 0）
 {
 lock（dtResult）
 {
 DataRow rowfound = null; （int i = 0; i< dtResult.Rows.Count; i ++）
 {
 DataRow row = dtResult.Rows [i]; 
 
 rowfound = dtRequired.Rows.Find（new object [] {row [0]，row [1]，row [2]，row [3]，row [4]，row [5]，row [6 ]，行[7]，行[8]}）; 
 if（rowfound！= null）
 {
 dtRequired.Rows.Remove（rowfound）; 
} 
} 
} 
} 
  

然而，上面的部分花费比方法1 花费的时间更长。
方法2 需要〜3秒的dtResult，1250行，dtRequired需要4500行。

方法有问题吗上文提到的？有没有更好的方法实现这一点？

解决方案

这是一个链接到使用LINQ to DataSet的MSDN页面，以获取两个数据表中显示的行。此示例使用相交。我想你可以使用除 之外的修改它。我不知道演出是否会更好。

I have two datatables. DataTable dtRequired and DataTable dtResult.

I want to output a datatable that contains rows that were not present in dtResponse but were found in dtRequired.

Approach 1 We have been using the algorithm specified at the following url http://weblogs.sqlteam.com/davidm/archive/2004/01/19/739.aspx. And this algorithm figured to be one of the slower ones in our profiling.

Approach 2 So, I tried to replace the above algo with something thats described below. dtRequired is indexed on the columns I m using below to Find the row.

    if (dtResult.Rows.Count > 0)
    {
        lock (dtResult)
        {
            DataRow rowfound = null;
            for (int i = 0; i < dtResult.Rows.Count; i++)
            {
                DataRow row = dtResult.Rows[i];
                rowfound = dtRequired.Rows.Find(new object[] { row[0], row[1], row[2], row[3], row[4], row[5], row[6], row[7], row[8] });
                if (rowfound != null)
                {
                    dtRequired.Rows.Remove(rowfound);
                }
            }                        
        }
    }

The above piece however is taking longer than the time taken by Approach 1. Approach 2 takes ~3 secs for dtResult with 1250 rows and dtRequired with 4500 rows.

Is something wrong with the approach I mentioned above? Is there any better approach of achieving this?

解决方案

This is a link to a MSDN page that use LINQ to DataSet to obtain the rows that appears in both datatables. This example use Intersect. I think you could modify it using except instead. I don't know if the performance will be better or not.

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