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}\tMessages:{1}\tCreateTime:\t{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();
}
}
}