Tips for Completing the Chapter Programming Challenges

Select a Chapter by Number:

• Chapter 7
• Chapter 8
• Chapter 9
• Chapter 10
• Chapter 11

Chapter 7

Programming Challenge 1: Reassign Task

When you reassign a task to a different member, you need to update both the TaskAssignment and Tasks tables. The following stored procedure can do both at the same time:

CREATE PROCEDURE spUpdateTaskAssignment
(
     @memberId int,
     @taskId int
)
AS
	UPDATE TaskAssignment
	SET Person_ID = @memberId
	WHERE Task_ID = @taskId;
	
	UPDATE Tasks
	Set Owner_ID = @memberId
	WHERE ID = @taskId

Programming Challenge 2: Edit Project Details

Here is a sample user interface for the window that lets the user edit project details. To add an employee to the project, the user selects an employee name and clicks the Add Member button. Implementing the add and remove functions are very easy, because the Projects class already has methods named AddPersonToProject and RemoveMember. The user can modify all fields except the Director. Just a reminder: only the project director should be allowed to edit the project details.

Programming Challenge 3: Remove Task

This is a relatively easy programming challenge to complete. Precondition: Only a project director should be permitted to remove a task. Tasks are stored in two places, so you must remember to delete the appropriate rows from both the TaskAssignment and Tasks table. These two tables participate in a relationship, in which TaskAssignment is the child and Tasks is the parent. Therefore delete from the TaskAssignment table first to avoid causing a Referential Integrity Constraint violation:

	DELETE FROM TaskAssignment
	WHERE Task_ID = @taskId
	AND Project_ID = @projectId
	
	DELETE FROM Tasks
	WHERE ID = @taskId
	AND Project_ID = @projectIdd

Chapter 8

Programming Challenge 5: Karate Payments Grid

This application, unlike the other examples in the chapter, requires you to join two tables from the Karate database: Members and Payments. It's easiest to join tables using the Query Builder tool, which you can activate when creating a data source. Notice the Configure Data Source window in Figure 8-69 (page 507). If you select the radio button that says Specify a custom SQL statement or stored procedure, the Query Builder tool will be available after you click the Next button.

Chapter 9

Programming Challenge 1: Computer Club Meeting

This challenge gives you practice creating a simple user interface design. You do not have to actually send any email messages. In our sample solution program, the user enters each message recipient's name into a TextBox (on the left) and clicks the Add Recipient button, which appends the name to the ListBox on the right:

Programming Challenge 2: Validating a DropDownList

There are two tricks to solving this programming challenge:

• Create a hidden TextBox containing "(select)". Use the CompareValidator control to compare the DropDown list to the TextBox.
• The second trick, if you want the error message to disappear as soon as the user selects an item from the DropDown list, is to avoid using the ValidationSummary control. Instead, just use the CompareValidator. The reason for this choice is that the ValidationSummary does not refresh its messages until after the form is posted back to the server. Here is a sample user interface, just after the user clicked the Submit button, without having made a choice from the DropDown list:

Programming Challenge 3: Checking a Date with CompareValidator

This is a very short assignment. In the sample design, shown below, we used a RequiredFieldValidator as well as a CompareValidator. If the date is entered in a format that Visual Basic does not understand, the error message is displayed:

Programming Challenge 4: Validating a Date Range

This project is short but tricky! There is an error in the description--you should use the RangeValidator control, not the CompareValidator. Aside from that, you can definitely set the MaximumValue and MinimumValue properties of the RangeValidator at runtime. Also, your code must call the RangeValidator's Validate method to make it all work. Here's a sample:

Chapter 10

Programming Challenge 1: ProjectTrackAw Application - Displaying a Confirmation Question

The easiest way to implement the confirmation question is to use a Panel control (the second choice). In our solution program, the panel contains a text question along with Yes and No Button controls. Initially, the Panel is invisible. When the user clicks the Join button, code statemens set the Panel's Visible property to True. The Click handlers for these two buttons both set the Panel's visible property to False. And, of course, the Click handler for the Yes button adds the person to the selected project. One other task is important: refresh the list of members if it is currently being displayed. Here is a sample of the confirmation question:

Programming Challenge 4: ProjectTrackAw with My Projects

At first, this project seems deceptively simple. Our solution program displays two LinkButton controls at the top, so the user can select All Projects or My Projects. The trickiest part of the coding is caused by the CreateCustomColumns method. You must find a way to call it only once, and not call it when the user clicks on the two LinkButtons. Otherwise, you will find that extra columns are added to the grid every time a button is clicked. Hint: consider using an If Not IsPostBack statement. Here is our sample: