c# - 在 asp.net 中停止后端操作

Question

如何在单击按钮执行期间停止数据库查询。这可能吗？我想在注销时结束数据库运行查询。

Answer 1

SqlCommand.Cancel 方法允许您停止 SQL 正在运行的查询：

如果没有要取消的内容，则不会发生任何事情。但是，如果有一个命令在处理中，并且尝试取消失败，则不会产生异常。

这是代码：

class Program
{
    private static SqlCommand m_rCommand;

    public static SqlCommand Command
    {
        get { return m_rCommand; }
        set { m_rCommand = value; }
    }

    public static void Thread_Cancel()
    {
        Command.Cancel();
    }

    static void Main()
    {
        string connectionString = GetConnectionString();
        try
        {
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                connection.Open();

                Command = connection.CreateCommand();
                Command.CommandText = "DROP TABLE TestCancel";
                try
                {
                    Command.ExecuteNonQuery();
                }
                catch { }

                Command.CommandText = "CREATE TABLE TestCancel(co1 int, co2 char(10))";
                Command.ExecuteNonQuery();
                Command.CommandText = "INSERT INTO TestCancel VALUES (1, '1')";
                Command.ExecuteNonQuery();

                Command.CommandText = "SELECT * FROM TestCancel";
                SqlDataReader reader = Command.ExecuteReader();

                Thread rThread2 = new Thread(new ThreadStart(Thread_Cancel));
                rThread2.Start();
                rThread2.Join();

                reader.Read();
                System.Console.WriteLine(reader.FieldCount);
                reader.Close();
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }
    static private string GetConnectionString()
    {
        // To avoid storing the connection string in your code,  
        // you can retrieve it from a configuration file. 
        return "Data Source=(local);Initial Catalog=AdventureWorks;"
            + "Integrated Security=SSPI";
    }
}