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从昨天开始我就一直在做这个，我只是无法更新我的数据库。有3张桌子。这是其中一个 WinForms 的一段代码。它加载数据并显示，但是在网格中手动更改某事后，我通过调用 Update 得到错误，或者根本没有发生任何事情。

请帮忙，因为我快疯了。

    public partial class Form3 : Form
    {
    //instance fields
    private export2Excel export2XLS;
    private DataSet _dataSet;
    private BindingSource _bsrc;
    private OleDbDataAdapter _dAdapter;
    private OleDbCommandBuilder _cBuilder;
    private DataTable _dTable;

    private void button1_Click(object sender, EventArgs e)
    {
        //create the connection string
        string connString = "Provider=Microsoft.Jet.OLEDB.4.0;Data      
        Source='C:\\Documents and Settings\\dorota\\Moje dokumenty\\Visual Studio  
        2010\\Projects\\WindowsFormsApplication1\\WindowsFormsApplication1\\artb.mdb'";

        //create the database query
        string query = "SELECT * FROM Samochody";
        System.Data.DataSet DtSet = new System.Data.DataSet();
        _dataSet = DtSet;
        //create an OleDbDataAdapter to execute the query
        OleDbDataAdapter dAdapter = new OleDbDataAdapter(query, connString);
        dAdapter.FillSchema(_dataSet, SchemaType.Source);

        _dAdapter = dAdapter;
        //create a command builder
        OleDbCommandBuilder cBuilder = new OleDbCommandBuilder(_dAdapter);
        _cBuilder = cBuilder;
        //create a DataTable to hold the query results
        DataTable dTable = new DataTable();
        _dTable = dTable;
        //fill the DataTable
        _dAdapter.Fill(_dTable);
        //_dAdapter.TableMappings.Add("Samochody", "Table");

        _dAdapter.Fill(_dataSet);

        // --------------------- to datagridview !

        //BindingSource to sync DataTable and DataGridView
        BindingSource _bsrc = new BindingSource();

        //set the BindingSource DataSource
        //bSource.DataSource = _dTable;
        _bsrc.DataSource = _dTable;
        //_bsrc = bSource;
        //set the DataGridView DataSource
        dataGridView1.DataSource = _bsrc;
    }
    }

和这里... ：

    private void sqlsave_Click(object sender, EventArgs e)
    {

        //int i=_dAdapter.Update(_dTable);
        _dAdapter.Update(_dataSet.Tables["Samochody"]);
        //_dAdapter.Update(_dataSet,"Samochody");
    }

//------------------------------------------------ ---------------------------------

行。我为此更改了 sqlsave 方法

    private void sqlsave_Click(object sender, EventArgs e)
    {

    try
    {
        //_dAdapter.Update(_dataSet.Tables["Samochody"]);
         OleDbCommand oldb= _cBuilder.GetUpdateCommand();
         int i=oldb.ExecuteNonQuery();
         System.Windows.Forms.MessageBox.Show(i+" rows affected.");
        //_dAdapter.Update(_dataSet,"Samochody");
    }catch(OleDbException oldbex){
        System.Windows.Forms.MessageBox.Show(oldbex.ToString());
    }

现在我终于得到了比“错误”更多的信息

System.Data.dll 中发生“System.InvalidOperationException”类型的未处理异常附加信息：ExecuteNonQuery 需要打开且可用的连接。连接的当前状态为关闭。

所以让我改变一下，如果是这样，我会告诉你的！

//--------------------------------

不。不。太快了，坚持不下去了。现在，在尝试保存时，我再次遇到异常，打开了连接，但是（我无法发布图像）当我调试它时，我看到我的 OleDbCommand 类型的对象为 _commandText

“UPDATE Samochody SET Item=?, Datadyspozycji autem od=?, ...”

等等。我想这就是原因。我对吗？该怎么办？

4

2 回答 2

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您没有为您的OleDbDataAdapter. 试试这样的：

该示例与您的代码不同，但它显示了 New Connection 的声明并将其传递给 OleDbDataAdapter

        string connetionString = null;
        OleDbConnection connection ;
        OleDbDataAdapter oledbAdapter ;
        OleDbCommandBuilder oledbCmdBuilder ;
        DataSet ds = new DataSet();
        int i = 0;
        string sql = null;
        connetionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Your mdb filename;";
        connection = new OleDbConnection(connetionString);
        sql = "select * from tblUsers";
        try
        {
            connection.Open();  // your code must have like this
            oledbAdapter = new OleDbDataAdapter(sql, connection);
            oledbCmdBuilder = new OleDbCommandBuilder(oledbAdapter);
            oledbAdapter.Fill(ds);
            for (i = 0; i <= ds.Tables[0].Rows.Count - 1; i++)
            {
                ds.Tables[0].Rows[i].ItemArray[2] = "neweamil@email.com";
            }
            oledbAdapter.Update(ds.Tables[0]);
            connection.Close();
            MessageBox.Show ("Email address updates !");
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
        }
于 2012-01-21T04:59:36.677 回答
0

我找到了答案：

但更好的方法是使用拖放并从代码中学习。

Select Data|View Datasources. Your dataset should be visible in the DataSources Window.
Drag a table to a (new) form. VS2005 will add a load of components and a few lines of code.

表单现在将有一个数据集实例，这是您的 Adapter.Fill 和 .Update 方法的参考点。

简单而且效果很好！:D
我在这里找到了它：https ://stackoverflow.com/a/548124/1141471

于 2012-01-21T18:58:14.580 回答