从DataGridView自动更新数据库中的值

Question

我目前正在使用MySql与C#结合的项目.DataGridView的数据由DB中多个表的连接提供.为了显示数据我使用以下,工作,代码:

adapter.SelectCommand = new MySqlCommand(
            " SELECT" +
            " l.lot AS Lot, "+
            " m.comment AS Bemerkungen," +
            ... (multiple columns from different tables) ...
            " FROM m " +
            " JOIN m2p ON m.m2p_id = m2p.id" +
            ... (more joins) ...
            , this._mySqlConnection);
dataGridView1.DataSource = data;
adapter.Fill(data);

现在允许GUI的用户修改某个列("注释"列).所以我为CellEndEdit事件分配了一个eventHandler ,当用户修改了允许的列时,adapter.Update(data)就调用了它.现在这不会执行正确的操作.

要定义我的updatecommand,我使用了以下代码:

adapter.UpdateCommand = new MySqlCommand(
                " UPDATE m" +
                " JOIN  l ON m.l_id = l.id" +
                " SET m.comment = @comment" +
                " WHERE l.lot = @lot"
                , this._mySqlConnection);
adapter.UpdateCommand.Parameters.Add("@comment", MySqlDbType.Text, 256, "Bemerkungen");
adapter.UpdateCommand.Parameters.Add("@lot", MySqlDbType.Text, 256, "Lot");

你能解释一下我如何修复我的代码以自动更新数据库吗？

编辑:添加进一步的源代码:

private MySqlDataAdapter warenlagerMySqlDataAdapter, kundenMySqlDataAdapter;
private DataTable warenlagerData, kundenData;
private DataGridView warenlagerGridView;

private void updateWarenlagerView(object sender, EventArgs e) {
            warenlagerMySqlDataAdapter.Update(warenlagerData);
}

private void initialzeFields() {
            warenlagerGridView.CellEndEdit += new DataGridViewCellEventHandler(this.updateWarenlagerView);
            warenlagerMySqlDataAdapter = new MySqlDataAdapter();
            warenlagerData = new DataTable();
            }

private void initializeWarenlagerView() {
            warenlagerMySqlDataAdapter.SelectCommand = new MySqlCommand(
                " SELECT" +
                " c.name AS Ursprung, " +
                " m2p.art_nr AS ArtNr," +
                " m.delivery_date AS Eingangsdatum," +
                " CONCAT(FORMAT(m.delivery_amount / 100, 2), 'kg') AS Eingangsmenge, " +
                " l.lot AS Lot," +
                " m.quality AS Qualität," +
                " m.comment AS Bemerkungen," +
                " CONCAT(m.units, 'kg') AS Units," +
                " CONCAT(FORMAT(s.amount / 100, 2), 'kg') AS Lagermenge, " +
                " FORMAT(m.base_price / 100, 2) AS Einkaufspreis," +
                " FORMAT(s.amount/10000 * m.base_price, 2) AS Wert" +
                " FROM mushrooms AS m " +
                " JOIN mushroom2path AS m2p ON m.mushroom2path_id = m2p.id" +
                " JOIN countries AS c ON m.origin_id = c.id" +
                " JOIN lots AS l ON m.lot_id = l.id" +
                " JOIN stock AS s ON s.mushrooms_id = m.id"
                , this._mySqlConnection);
            warenlagerGridView.DataSource = warenlagerData;
            warenlagerMySqlDataAdapter.Fill(warenlagerData);
            warenlagerMySqlDataAdapter.UpdateCommand = new MySqlCommand(
                " UPDATE mushrooms AS m" +
                " JOIN lots AS l ON m.lot_id = l.id" +
                " SET m.comment = @comment" +
                " WHERE l.lot = @lot"
                , this._mySqlConnection);
            warenlagerMySqlDataAdapter.UpdateCommand.Parameters.Add("@comment", MySqlDbType.Text, 256, "Bemerkungen");
            warenlagerMySqlDataAdapter.UpdateCommand.Parameters.Add("@lot", MySqlDbType.Text, 256, "Lot");
        }

这是关于这个问题的整个代码.我100%确定adapter.Update(data)调用该方法(调试).传递给adapter.Update()方法的数据包含新数据.

Answer 1

您的更新声明不正确。它应该是：

"UPDATE m FROM mushrooms m JOIN lots l ON m.lot_id = l.id SET m.comment = @comment WHERE l.lot = @lot"