C#

class App {

   // Definition of delegate that allows quering a component's status
   delegate String GetStatus();

   static void Main() {
      // Declare an empty delegate chain
      GetStatus getStatus = null;

      // Construct the 3 components and add their status methods 
      // to the delegate chain
      getStatus += new GetStatus(new Light().SwitchPosition);
      getStatus += new GetStatus(new Fan().Speed);
      getStatus += new GetStatus(new Speaker().Volume);

      // Show consolidated status report reflecting 
      // the condition of the 3 components
      Console.WriteLine(GetComponentStatusReport(getStatus));
   }

   // Method that queries several components and returns a status report
   static String GetComponentStatusReport(GetStatus status) {

      // If the chain is empty, there is nothing to do
      if (status == null) return null;

      // Use this to build the status report
      StringBuilder report = new StringBuilder();

      // Get an array where each element is a delegate from the chain
      Delegate[] arrayOfDelegates = status.GetInvocationList();

      // Iterate over each delegate in the array 
      foreach (GetStatus getStatus in arrayOfDelegates) {

         try {
            // Get a component's status string and append it to the report
            report.Append(getStatus() + "\r\n\r\n");
         }
         catch (Exception e) {
            // Generate an error entry in the report for this component
            Object component = getStatus.Target;
            report.Append("Failed to get status from " +
               ((component == null) ? "" : component.GetType() + ".") + 
               getStatus.Method.Name + 
               "\r\n   Error: " + e.Message + "\r\n\r\n");
         }
      }

      // Return the consolidated report to the caller
      return report.ToString();
   }
}

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"When the only tool you have is a hammer, a sore thumb you will have."

CREATE PROCEDURE Get
@ID PK_SMALLINT = NULL 

Select * from Table 
where ( (@ID IS NULL) or (ID = @ID) )