从 DataTable C# 添加到 OLE 类型表答案

【问题标题】：Adding to OLE type table from DataTable C#从 DataTable C# 添加到 OLE 类型表
【发布时间】：2017-01-30 18:28:37
【问题描述】：

我正在尝试使用来自 DataTable 对象的集合 DataRows 将数据添加到 Access 表中，并在查看器中看到一组很好的数据 (43) 记录，但它填充了相同的记录 43 次。我的参数设置错误还是我做错了什么？

private void PopulateDB(DataTable dtDB)
    {
        lblDataStatus.Text = "populating master table...";
        this.Refresh();
        progressBar1.Visible = true;
        progressBar1.Value = 1;
        progressBar1.Maximum = dtDB.Rows.Count;
        string strConn = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=\\path\fname.accdb";
        using (OleDbConnection conn = new OleDbConnection (strConn ))
        {
            using (OleDbCommand cmd = new OleDbCommand())
            {
                foreach (DataRow dr in dtDB .Rows)
                {
                    progressBar1.PerformStep();
                try
                {
                    cmd.CommandText = "INSERT INTO PMADocMaster( PN, PNNewRev, PN8Digit, ECO, Mon, SupNum, URL ) VALUES (?,?,?,?,?,?,?)";
                    cmd.Parameters.Add("@pn", OleDbType.VarChar).Value = dr.Field<string>("PNFullNum");
                    cmd.Parameters.Add("@rev", OleDbType.VarChar).Value = dr.Field<string>("PNNewRev");
                    cmd.Parameters.Add("@pn8", OleDbType.VarChar).Value = dr.Field<string>("PN8Dig");
                    cmd.Parameters.Add("@eco", OleDbType.VarChar).Value = dr.Field<string>("ECO");
                    cmd.Parameters.Add("@mon", OleDbType.VarChar).Value = dr.Field<string>("Mon");
                    cmd.Parameters.Add("@supnum", OleDbType.VarChar).Value = dr.Field<string>("SupNum");
                    cmd.Parameters.Add("@url", OleDbType.VarChar).Value = dr.Field<string>("URL");
                    cmd.Connection = conn;
                    conn.Open();
                    cmd.ExecuteNonQuery();
                    conn.Close();
                }
                catch (Exception e)
                {
                    MessageBox.Show("Error: " + e.Message);
                    lblDataStatus.Text = e.Message;
                    return;
                    // duplicates are happening, will check veracity of data afterwards
                }
                }
                progressBar1.Visible = false;
            }
        }
    }

【问题讨论】：

如果您使用 DataAdapter，它将为您完成所有更新。从 DataTable 中提取数据以发送到 DB 是相当奇怪的

标签： c# ms-access datatable oledb

【解决方案1】：

您可以使用 cmd.Parameters.clear() 或优化您的代码，如下所示..

private void PopulateDB(DataTable dtDB)
    {
        lblDataStatus.Text = "populating master table...";
        this.Refresh();
        progressBar1.Visible = true;
        progressBar1.Value = 1;
        progressBar1.Maximum = dtDB.Rows.Count;
        string strConn = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=\\path\fname.accdb";
        using (OleDbConnection conn = new OleDbConnection(strConn))
        {
            using (OleDbCommand cmd = new OleDbCommand("INSERT INTO PMADocMaster( PN, PNNewRev, PN8Digit, ECO, Mon, SupNum, URL ) VALUES (?,?,?,?,?,?,?)",conn))
            {
                try
                {
                    cmd.Parameters.Add("@pn");, OleDbType.VarChar);
                    cmd.Parameters.Add("@rev", OleDbType.VarChar);
                    cmd.Parameters.Add("@pn8", OleDbType.VarChar);
                    cmd.Parameters.Add("@eco", OleDbType.VarChar);
                    cmd.Parameters.Add("@mon", OleDbType.VarChar);
                    cmd.Parameters.Add("@supnum", OleDbType.VarChar);
                    cmd.Parameters.Add("@url", OleDbType.VarChar);
                    conn.Open();
                    foreach (DataRow dr in dtDB.Rows)
                    {
                        progressBar1.PerformStep();

                        cmd.Parameters["@pn"].Value = dr.Field<string>("PNFullNum");
                        cmd.Parameters["@rev"].Value = dr.Field<string>("PNNewRev");
                        cmd.Parameters["@pn8"].Value = dr.Field<string>("PN8Dig");
                        cmd.Parameters["@eco"].Value = dr.Field<string>("ECO");
                        cmd.Parameters["@mon"].Value = dr.Field<string>("Mon");
                        cmd.Parameters["@supnum"].Value = dr.Field<string>("SupNum");
                        cmd.Parameters["@url"].Value = dr.Field<string>("URL");
                        cmd.ExecuteNonQuery();
                    }

                    conn.Close();
                }
                catch (Exception e)
                {
                    MessageBox.Show("Error: " + e.Message);
                    lblDataStatus.Text = e.Message;
                    return;
                    // duplicates are happening, will check veracity of data afterwards
                }
                progressBar1.Visible = false;
            }
        }
    }

【讨论】：