問題描述

我正在 ADO.NET 中手動編寫事務代碼.我正在使用的示例重用了 SqlCommand，這看起來是個好主意.

I'm coding a transaction manually in ADO.NET. The example I'm working from reuses the SqlCommand which seem like a fine idea.

但是，我在命令中添加了參數.

However, I have added parameters to my command.

我的問題是:在下面的代碼中，command.Parameters.Clear() 是否正確?還是我做錯了?

My question is: in the following code, is command.Parameters.Clear() correct? Or am I doing it wrong?

using (var connection = new SqlConnection(EomAppCommon.EomAppSettings.ConnStr))
{
    connection.Open();
    SqlTransaction transaction = connection.BeginTransaction();
    SqlCommand command = connection.CreateCommand();
    command.Transaction = transaction;
    try
    {
        foreach (var itemIDs in this.SelectedItemIds)
        {
            command.CommandText = "UPDATE Item SET payment_method_id = @batchID WHERE id in (@itemIDs)";
            // IS THE FOLLOWING CORRECT?
            command.Parameters.Clear();

            command.Parameters.Add(new SqlParameter("@batchID", batchID));
            command.Parameters.Add(new SqlParameter("@itemIDs", itemIDs));
            command.ExecuteNonQuery();
        }
        transaction.Commit();
    }
    catch (Exception ex)
    {
        MessageBox.Show("Failed to update payment batches, rolling back." + ex.Message);
        try
        {
            transaction.Rollback();
        }
        catch (Exception exRollback)
        {
            if (!(exRollback is InvalidOperationException)) // connection closed or transaction already rolled back on the server.
            {
                MessageBox.Show("Failed to roll back. " + exRollback.Message);
            }
        }
    }
}

推薦答案

由于您重復執行相同的查詢，因此沒有必要清除它們 - 您可以將參數添加到循環外，只需將它們填充到內即可.

Since you're repeatedly executing the same query, it's unnecessary to clear them - you can add the parameters outside the loop and just fill them inside.

try
{
    command.CommandText = "UPDATE Item SET payment_method_id = @batchID WHERE id in (@itemIDs)";
    command.Parameters.Add(new SqlParameter("@batchID", 0));
    command.Parameters.Add(new SqlParameter("@itemIDs", ""));

    foreach (var itemIDs in this.SelectedItemIds)
    {
        command.Parameters["@batchID"].Value = batchID;
        command.Parameters["@itemIDs"].Value = itemIDs;
        command.ExecuteNonQuery();
    }
    transaction.Commit();
}

注意 - 您不能在此處使用帶有 IN 的參數 - 它不會工作.

Note - you can't use parameters with IN as you've got here - it won't work.

這篇關于重用帶有事務的 SqlCommand 時，我應該調用 Parameters.Clear 嗎?的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！