使用SqlDependency监听MSSQL数据库表变化通知

SqlDependency提供了这样一种机制，当被监测的数据库中的数据发生变化时，SqlDependency会自动触发OnChange事件来通知应用程序，从而达到让系统自动更新数据(或缓存)的目的。

首先要对数据库进行配置，配置命令如下：

1.启用Service Broker并查看是否启用成功，is_broker_enabled为1则表明启用成功：

ALTER DATABASE SqlDepTest SET NEW_BROKER WITH ROLLBACK IMMEDIATE;
ALTER DATABASE SqlDepTest SET ENABLE_BROKER;
SELECT is_broker_enabled FROM sys.databases WHERE name = 'SqlDepTest'

2.开启帐号订阅权限，由于sa帐号不支持权限设置，所以需要建立单独的帐号。

use master

GRANT CREATE PROCEDURE TO sqldep
GRANT CREATE QUEUE TO sqldep
GRANT CREATE SERVICE TO sqldep

use master
GRANT SUBSCRIBE QUERY NOTIFICATIONS TO sqldep
exec sp_helprotect NULL, sqldep

C#示例代码如下：

private const string SQL_CONNECTIONSETTINGS = "";

static void Main(string[] args)
{
    //传入连接字符串,启动基于数据库的监听
    SqlDependency.Start(SQL_CONNECTIONSETTINGS);
    HandleMessage();

    Console.Read();
}

/// <summary>
/// 触发处理消息机制
/// </summary>
private static void HandleMessage()
{
    using (SqlConnection connection = new SqlConnection(SQL_CONNECTIONSETTINGS))
    {
        //依赖是基于某一张表的,而且查询语句只能是简单查询语句,不能带top或*,同时必须指定所有者,即类似[dbo].[]
        using (SqlCommand command = new SqlCommand("SELECT [MessageID],[Messages],[CreateTime] FROM [dbo].[Messages]", connection))
        {
            int messageID = 0;
            command.CommandType = CommandType.Text;
            connection.Open();
            command.Notification = null;
            SqlDependency dependency = new SqlDependency(command);
            dependency.OnChange += new OnChangeEventHandler(Dependency_OnChange);

            SqlDataReader sdr = command.ExecuteReader();
            while (sdr.Read())
            {
                int.TryParse(sdr["MessageID"].ToString(), out messageID);
                ProcessMessage(messageID);
                Console.WriteLine("MessageID:{0}	Messages:{1}	CreateTime:	{2}", sdr["MessageID"].ToString(), sdr["Messages"].ToString(), sdr["CreateTime"].ToString());
                CompleteProcessMessage(messageID, 2);
            }
            sdr.Close();
        }
    }
}

/// <summary>
/// SQL消息触发事件
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private static void Dependency_OnChange(object sender, SqlNotificationEventArgs e)
{
    SqlDependency dependency = sender as SqlDependency;
    dependency.OnChange -= Dependency_OnChange;
    HandleMessage();
}

/// <summary>
/// 处理消息
/// </summary>
/// <param name="messageID">消息编号</param>
private static void ProcessMessage(int messageID)
{
    using (SqlConnection connection = new SqlConnection(SQL_CONNECTIONSETTINGS))
    {
        string sql = string.Format(@"INSERT INTO [dbo].[MessagesComplete]
                       SELECT [MessageID],[Messages],1,[CreateTime],GETDATE()
                       FROM [dbo].[Messages] WHERE [MessageID] = {0}
                       DELETE FROM [dbo].[Messages] WHERE [MessageID] = {0}", messageID);
        using (SqlCommand command = new SqlCommand(sql, connection))
        {
            command.CommandType = CommandType.Text;
            connection.Open();
            command.ExecuteNonQuery();
            command.Dispose();
        }
    }
}
/// <summary>
/// 消息处理完成，更新消息处理状态
/// </summary>
/// <param name="messageID">消息编号</param>
/// <param name="status">状态：1.处理中，2.处理完成，-1.处理失败</param>
private static void CompleteProcessMessage(int messageID, int status)
{
    using (SqlConnection connection = new SqlConnection(SQL_CONNECTIONSETTINGS))
    {
        string sql = string.Format("UPDATE [dbo].[MessagesComplete] SET [Status] = {1} WHERE [MessageID] = {0}", messageID, status);
        using (SqlCommand command = new SqlCommand(sql, connection))
        {
            command.CommandType = CommandType.Text;
            connection.Open();
            command.ExecuteNonQuery();
            command.Dispose();
        }
    }
}