SqlDependency dihapus setelah acara diaktifkan sehingga Anda perlu menjalankan perintah lagi dengan dependensi. Di bawah ini adalah contoh aplikasi konsol yang akan berlangganan lagi kecuali pemberitahuan itu karena kesalahan.
using System;
using System.Data;
using System.Data.SqlClient;
namespace SqlDependencyExample
{
class Program
{
static string connectionString = @"Data Source=.;Initial Catalog=YourDatabase;Application Name=SqlDependencyExample;Integrated Security=SSPI";
static void Main(string[] args)
{
SqlDependency.Start(connectionString);
getDataWithSqlDependency();
Console.WriteLine("Waiting for data changes");
Console.WriteLine("Press enter to quit");
Console.ReadLine();
SqlDependency.Stop(connectionString);
}
static DataTable getDataWithSqlDependency()
{
using (var connection = new SqlConnection(connectionString))
using (var cmd = new SqlCommand("SELECT Col1, Col2, Col3 FROM dbo.MyTable;", connection))
{
var dt = new DataTable();
// Create dependency for this command and add event handler
var dependency = new SqlDependency(cmd);
dependency.OnChange += new OnChangeEventHandler(onDependencyChange);
// execute command to get data
connection.Open();
dt.Load(cmd.ExecuteReader(CommandBehavior.CloseConnection));
return dt;
}
}
// Handler method
static void onDependencyChange(object sender,
SqlNotificationEventArgs e)
{
Console.WriteLine($"OnChange Event fired. SqlNotificationEventArgs: Info={e.Info}, Source={e.Source}, Type={e.Type}.");
if ((e.Info != SqlNotificationInfo.Invalid)
&& (e.Type != SqlNotificationType.Subscribe))
{
//resubscribe
var dt = getDataWithSqlDependency();
Console.WriteLine($"Data changed. {dt.Rows.Count} rows returned.");
}
else
{
Console.WriteLine("SqlDependency not restarted");
}
}
}
}
