SqlDataAdapter.Update直到第二次更新才写入表

Question

我有一个用C＃2010 Express开发的程序，其中包含一个由DataGridView组成的表单，下面有单独的单元格编辑字段。选择行（在其左端单击）时，行中的值将复制到编辑字段中。进行更改，单击Memorize Transaction按钮。新值显示在DataGridView中。如果表格随后关闭并重新打开（处理并重新加载），则会显示原始值，而不是新值。显然，数据库记录没有更新。

如果重复上述过程，除了在关闭表单之前再次选择记录并再次单击Memorize Transaction按钮时，值IS存储在数据库中。关闭表单然后重新打开时，将显示新值。

显然，在第一次点击Memorize Transaction按钮时，值会立即存储在数据库中。

以下声明显示在表单类的顶部：

    DataTable _dt;
    SqlDataAdapter _adapter;

方法load_DataGridView（）如下所示。请注意，适配器的Update，Delete和Insert查询是通过调用SqlCommandBuilder的各自GetXXXCommand（）方法构建的。调试期间的断点表明这些断点已正确填充。

    private void load_dataGridView()
    {
        DataTable dt = new DataTable();
        _dt = dt;
        SqlConnection dbconn = new SqlConnection(dbq.connectionString);
        dbconn.Open();
        string qstr = @"SELECT transaction_id
    , 0 as pay
    , m.has_splits
    , m.Num
    , m.Type
    , m.last_date
    , m.next_date
    , m.Payee
    , m.Memo
    , m.Tax_Category
    , m.Amount
    , m.Clr
    , m.Initials
    , m.sales_tax_paid
    , m.from_institution_id as FromInstitutionID
    , m.from_institution as FromInstitution
    , m.from_account_id as FromAccountID
    , m.from_account as FromAccount
    , m.from_envelope_id as FromEnvelopeID
    , m.from_envelope as FromEnvelope
    , m.to_institution_id as ToInstitutionID
    , m.to_institution as ToInstitution
    , m.to_account_id as ToAccountID
    , m.to_account as ToAccount
    , m.to_envelope_id as ToEnvelopeID
    , m.to_envelope as ToEnvelope
    , m.frequency
    FROM memorized m
    ";
        SqlDataAdapter adapter = new SqlDataAdapter(qstr,dbconn);
        SqlCommandBuilder scb = new SqlCommandBuilder(adapter);
        adapter.UpdateCommand = new SqlCommandBuilder(adapter).GetUpdateCommand();
        adapter.DeleteCommand = new SqlCommandBuilder(adapter).GetDeleteCommand();
        adapter.InsertCommand = new SqlCommandBuilder(adapter).GetInsertCommand();
        _adapter = adapter;
        _adapter.Fill(_dt);
        build_dgv_columns(Properties.Settings.Default.currentInstitutionId,
        Properties.Settings.Default.currentAccountId);
        memorizedDataGridView.DataSource = _dt;
    }

单击Memorize Transaction按钮时调用的代码如下：

    private void bnMemorizeTx_Click(object sender, EventArgs e)
    {
        if (_newTx)
        {
            _currentTxRow = _dt.Rows.Count;
            _dt.Rows.Add();
            _newTx = false;
        }
        else
        {
            _currentTxRow = memorizedDataGridView.SelectedRows[0].Index;
        }
        populateRowFromFields(memorizedDataGridView.Rows[_currentTxRow]);
        memorizedDataGridView.Refresh();
        memorizedDataGridView.ClearSelection();
        //grid shows new value with no rows selected at this point, row is "dirty"
        try
        {
            _adapter.Update(_dt);
        }
        catch (SqlException e1)
        {
            MessageBox.Show(e1.Message + e1.InnerException, "Error Thrown",MessageBoxButtons.OK);
        }
        reset_transaction_fields();
    }

不会抛出异常。我怀疑将数据从DataGridView中拉出到编辑字段然后以某种方式再次将其写回_adapter.Update（_dt）命令能够检测到行已被更改的操作，因此当它被调用时，它不会不要更新任何东西。然后在第二次尝试时，当重新选择行（显示新值）但没有进行编辑更改时，它确实有效。不知何故，即使新值出现在网格中，也就像未提交更改一样，必须重新选择行才能实现。

populateRowFromFields方法如下所示，通过使用单元格索引的列名引用将编辑字段中的值写回行中的单元格值：

            private void populateRowFromFields(DataGridViewRow dgvr)
    {
        dgvr.Cells["Num"].Value = tbRefNum.Text;
        dgvr.Cells["Type"].Value = cbType.GetItemText(cbType.SelectedItem);
        dgvr.Cells["last_date"].Value = dtpLastPaid.Value.ToShortDateString();
        dgvr.Cells["next_date"].Value = dtpNextPay.Value.ToShortDateString();
        dgvr.Cells["Payee"].Value = tbPayee.Text;
        dgvr.Cells["Amount"].Value = tbAmount.Text;
        dgvr.Cells["FromInstitutionID"].Value = cbFromInst.GetItemText(cbFromInst.SelectedValue); // fromInst
        dgvr.Cells["FromInstitution"].Value = cbFromInst.GetItemText(cbFromInst.SelectedItem); // fromAcct
        dgvr.Cells["FromAccountID"].Value = cbFromAcct.GetItemText(cbFromAcct.SelectedValue); // fromEnv
        dgvr.Cells["FromAccount"].Value = cbFromAcct.GetItemText(cbFromAcct.SelectedItem); // fromInst
        dgvr.Cells["FromEnvelopeID"].Value = cbFromEnv.GetItemText(cbFromEnv.SelectedValue); // fromAcct
        dgvr.Cells["FromEnvelope"].Value = cbFromEnv.GetItemText(cbFromEnv.SelectedItem); // fromEnv
        if ((cbType.GetItemText(cbType.SelectedItem) == "+iTx") || (cbType.GetItemText(cbType.SelectedItem) == "-iTx") || (cbType.GetItemText(cbType.SelectedItem) == "+eTx") || (cbType.GetItemText(cbType.SelectedItem) == "-eTx")) 
        {
            dgvr.Cells["ToInstitutionID"].Value = cbToInst.GetItemText(cbToInst.SelectedValue); // toInst
            dgvr.Cells["ToInstitution"].Value = cbToInst.GetItemText(cbToInst.SelectedItem); // toInst
            dgvr.Cells["ToAccountID"].Value = cbToAcct.GetItemText(cbToAcct.SelectedValue); // toAcct
            dgvr.Cells["ToAccount"].Value = cbToAcct.GetItemText(cbToAcct.SelectedItem); // toAcct
            dgvr.Cells["ToEnvelopeID"].Value = cbToEnv.GetItemText(cbToEnv.SelectedValue); // toEnv
            dgvr.Cells["ToEnvelope"].Value = cbToEnv.GetItemText(cbToEnv.SelectedItem); // toEnv
            hideTxToFields();
        }
        dgvr.Cells["Memo"].Value = tbMemo.Text;
        dgvr.Cells["Tax_Category"].Value = cbTaxCategory.GetItemText(cbTaxCategory.SelectedItem); // taxCategory
        dgvr.Cells["sales_tax_paid"].Value = cbSalesTaxPaid.GetItemText(cbSalesTaxPaid.SelectedItem); // salesTaxPaid
        dgvr.Cells["Clr"].Value = "U";
        dgvr.Cells["Initials"].Value = cbBy.GetItemText(cbBy.SelectedItem); // by
        dgvr.Cells["frequency"].Value = cbFrequency.GetItemText(cbFrequency.SelectedItem); // frequency
    }

帮助！这让我疯了！

Answer 1

最简单的选择是通过BindingSource对网格和编辑控件使用数据绑定，例如

private SqlConnection connection;
private SqlDataAdapter adapter;
private SqlCommandBuilder builder;
private DataTable table;

private void Form1_Load(object sender, EventArgs e)
{
    connection = new SqlConnection("connection string here");
    adapter = new SqlDataAdapter("SELECT * FROM Person", connection);
    builder = new SqlCommandBuilder(adapter);
    table = new DataTable();

    adapter.Fill(table);
    bindingSource1.DataSource = table;
    dataGridView1.DataSource = bindingSource1;
    givenNameTextBox.DataBindings.Add("Text", bindingSource1, "GivenName");
    familyNameTextBox.DataBindings.Add("Text", bindingSource1, "FamilyName");
}

private void addButton_Click(object sender, EventArgs e)
{
    bindingSource1.AddNew();
}

private void deleteButton_Click(object sender, EventArgs e)
{
    bindingSource1.RemoveCurrent();
}

private void saveButton_Click(object sender, EventArgs e)
{
    bindingSource1.EndEdit();
    adapter.Update(table);
}