Answers to Chapter 9

Reviewing It

1: Explain the difference between the HTP package and the HTF package.
A1: The HTP package contains PL/SQL procedures that generate HTML output, whereas the HTF package contains PL/SQL functions that return HTML code as the return value
2: What is htp.p used for?
A2: htp.p can be used to pass the text <HTML> to the HTML output
3: Why would you want to call another PL/SQL procedure in a Web environment?
A3: This called pl/sql is a way of giving a consistent look with appearances and error messages across the Web site
4: In Listing 9.9, line 4, why is the p_inv_id variable set to null?
A4: To provide the procedure with a default value in the case that no value was passed, the Web page displays with the lowest inv_id record in the database
5: In Listing 9.10, what error message will be displayed if the car requested cannot be found?
A5: 42:p_text => 'The auto selected could not be found'.

Checking It

1: If you have an htp.bodyopen command you need an

  1. Htp.htlmopen

  2. Htp.htlmclose

  3. Htp.bodyclose

  4. Htp.textopen

A1: c
2: What happens if an input parameter does not have a default value and none is passed?

  1. Nothing happens, the Web page displays as programmed

  2. An error is returned to the user complaining about a missing mandatory parameter

  3. The results may be unpredictable as the Web page will try to display the variable

  4. The Web server will crash

A2: b
3: When using PL/SQL, you do not need a virtual path at all.

True/False

A3: False, the virtual path tells the Web server that this is a PL/SQL.

Applying It

Independent Exercise 1:

  • Start your favorite editor and put the few HTML commands in to simply display your name.

  • Name this file Ch9_ex1.htm.

  • Access this file with your favorite Web browser.

Independent Exercise 2:

  • Start your favorite editor and build and compile a simple PL/SQL procedure that performs the same task as Exercise 1 except use the PL/SQL htp package to create the HTML.

Independent Exercise 3:

  • Create a small table object with one character field.

  • Build a simple PL/SQL Web-based procedure that

    • Prompts the user for a variable.

    • Checks to make sure something was entered.

    • Inserts into your table object the contents of this variable.

    • Displays what has been inserted.

    • Clears the entry field so that additional information can be entered.

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