Again, using the Hotel schema, draw a relational algebra tree for each of the following queries and use the heuristic rules given in Section 23.3.2 to transform the queries into a more efficient form:
(a) SELECT r.roomNo, r.type, r.price
FROM Room r, Booking b, Hotel h
WHERE r.roomNo = b.roomNo AND b.hotelNo = h.hotelNo AND
h.hotelName = ‘Grosvenor Hotel’ AND r.price > 100;
(b) SELECT g.guestNo, g.guestName
FROM Room r, Hotel h, Booking b, Guest g
WHERE h.hotelNo = b.hotelNo AND g.guestNo = b.guestNo AND
h.hotelNo = r.hotelNo AND h.hotelName = ‘Grosvenor Hotel’ AND
dateFrom >= ‘1-Jan-04’ AND dateTo <= ‘31-Dec-04’;
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Analyze the following code:
``` import javafx.application.Application; import javafx.scene.Scene; import javafx.scene.layout.HBox; import javafx.scene.layout.Pane; import javafx.geometry.Insets; import javafx.stage.Stage; import javafx.scene.image.Image; import javafx.scene.image.ImageView; public class Test extends Application { @Override // Override the start method in the Application class public void start(Stage primaryStage) { // Create a pane to hold the image views Pane pane = new HBox(10); pane.setPadding(new Insets(5, 5, 5, 5)); Image image = new Image("www.cs.armstrong.edu/liang/image/us.gif"); pane.getChildren().addAll(new ImageView(image), new ImageView(image)); // Create a scene and place it in the stage Scene scene = new Scene(pane); primaryStage.setTitle("ShowImage"); // Set the stage title primaryStage.setScene(scene); // Place the scene in the stage primaryStage.show(); // Display the stage } /** * The main method is only needed for the IDE with limited * JavaFX support. Not needed for running from the command line. */ public static void main(String[] args) { launch(args); } }``` a. The program runs fine and displays two images. b. new Image("www.cs.armstrong.edu/liang/image/us.gif") must be replaced by new Image("http://www.cs.armstrong.edu/liang/image/us.gif"). c. The image object cannot be shared by two ImageViews. d. The addAll method needs to be replaced by the add method.
Briefly describe the .xml files used to control USMT.
What will be an ideal response?
LRU replaces the page that has spent the ________.
a) longest time in memory b) longest time in memory without being referenced c) shortest time in memory d) shortest time in memory without being referenced
A collection of design choices that includes colors, fonts, and special effects used to give a consistent look to a document, workbook, or presentation.
What will be an ideal response?