关于c＃：Dataset.GetChanges（DataRowState.Modified）返回null

Dataset.GetChanges(DataRowState.Modified) return null

我想问一下C.NET的情况

为什么我的dataset.getchanges(datarowstate.modified)返回空值？

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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;



namespace test_for_error
{
public partial class Form1 : Form
{
private SqlDataAdapter _DataAdapter;
private DataSet _DataSet;


<wyn> public Form1()
{
InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e)
{
SqlConnection cn = new SqlConnection(@"Data Source=BEB7WILLOW\BEB7WILLOW;
Database=Cost_Estimate_DB;
Trusted_Connection=No;
User ID=sa;
password=s@password1");

_DataAdapter = new SqlDataAdapter("select client_name from cost_estimate", cn);

_DataSet = new DataSet();
_DataAdapter.Fill(_DataSet,"cost_estimate");
this.txtClient.DataBindings.Add("Text", _DataSet,"cost_estimate.client_name", true, DataSourceUpdateMode.OnPropertyChanged);

}

private void btnSave_Click(object sender, EventArgs e)
{
_DataSet.AcceptChanges();
DataSet DatasetChanges = _DataSet.GetChanges(DataRowState.Modified);
}
}

}

在DataSet.getChanges之前调用DataSet.AcceptChanges，这将重置行状态，因此不会修改任何内容。

"The RowState property of each DataRow also changes; Added and Modified rows become Unchanged, and Deleted rows are removed."

试一试

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private void btnSave_Click(object sender, EventArgs e)
{
DataSet DatasetChanges = _DataSet.GetChanges();
_DataSet.AcceptChanges();
}