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IT130 Notes -- 6/1/09

Review Questions

1. After changing the SQL statement, what must one do to reload the DataSet and use it to populate the databound control?
   Ans: Call the DataBind method of the control where the data is to be displayed.
    
2. I don't get any compiler errors when I run my ASP.Net project with this repeater, but I don't get any output. What is wrong?

   <asp:Repeater ID=repDisplay runat=server
                 DataSourceID=adsGroceries>
   </asp:Repeater>
   

   Ans: There are no templates. Here are some possible templates HeaderTemplate, ItemTemplate, AlternatingTemplate, SeperatorTemplate, FooterTemplate.
    
3. What are the steps to inserting a new row in a database table?
   Ans: Create and configure a Connection object, create and configure a Command object with an INSERT SQL statement and connection, call the ExecuteNonQuery for the command object, close the connection.

Applying CSS Classes to Asp.Net Controls

• Here is how to create a CSS class and apply it to a control using VS:
   
  
  1. Add a stylesheet named styles.css to the project: Project >> Add New Item >> Choose Stylesheet Templage >> Change the name to styles.css
      
  2. Attach the stylesheet to page1.css: Format >> Attach stylesheet. Select styles.css.
      
  3. Add a new class named .orange: right click on stylesheet >> Add style rule >> Click Class name >> Enter orange for class name >> Click OK.
      
  4. Set the properties and values of .orange: Select .orange on the stylesheet >> Right click on the stylesheet >> Build style >> Add the desired properties and values for .orange.
      
  5. Attach the class to a control: Go to the properties window of the control >> Set the CssClass.

Password Encryption

• Modern login systems all use some sort of password encryption.
   
• In one of the simplest systems, used in Example 69 (login-page2.aspx), use a one-way hash algorithm, like SHA (Shared Hash Algorithm). The encoded passwords are stored in a file on the server. When a user logs in, his or her password is encoded and compared with with the encoded passwords and usernames in the file. If there is a match, the login is successful.
   
• Here is a Wikipedia Article on SHA
   
• For Example 69, the encrypted passwords are stored in Base-64. Here is a Base-64 Conversion Table for converting binary data to base-64 and vice versa.
   
• Practice Problem. Convert the following hex data into base-64:
  

  4E A2 9B 73
  

More Controls

• LinkButton   Set the PostBackUrl to http://www.disney.com.
   
• ImageButton   Use mickey.jpg as the image; also set the PostBackUrl to http://www.disney.com.
   
• ImageMap   Here is a map of the USA that could be used in an ImageMap control.

Master Pages

• Sometimes several pages in a website contain common information.
   
• An alternative to copying the same common items to each page in the website is to use a master page: take the items that are repeated on each content page and move these items to a master page where they are entered only entered once.
   
• The items that are unique are placed on the content pages.
   
• Each content page has a reference to its master page.
   
• See Example 68 (Master Pages).
   

Cookies

• A cookie is a piece of data that server-side application stores on the users harddrive.
   
• Cookies usually have an expiration date, at which point in time they are erased.
   
• ASP.Net stores cookie information in an HttpCookie object.
   
• Use Request.Cookies to obtain an HttpCookie from the user's harddrive.
   
• Use Response.Cookies to write a cookie to the user's harddrive.
   
• Cookies should not be used to store sensitive information like credit card numbers.
   
• Cookies are often used to store information entered on forms to save the user the trouble of entering the same information repeatedly.
   
• See Example 67 (cookies.aspx).