A QUICK TOUR OF POWERBUILDER ENVIRONMENT

Assignment 2 - IFS 320 - Database Management Systems

Author: Dr. Vijay Raghavan

Objective:

• To understand the PowerBuilder working environment,
• To get an overview of navigating within this environment,
• To learn how some window controls are used within PowerBuilder, and
• To Build a foundation for studying PB in greater detail.

CREATE A SIMPLE POWER BUILDER APPLICATION

PowerBuilder development environment consists of many painters that can be accessed from a toolbar. In this exercise, we will use some of these painters to create different PB objects. Many of these toolbar buttons can launch a particular painter which you can use to create or modify a PB object. Thus, the application painter can create an application object, window painter a window object and so on. As you start each painter, you will see a painter bar in addition to the main toolbar. These painterbars contain many painterbar buttons that can be used to do things that are particular to this painter.

Step 1: Create a library

Launch PB, go to the library painter and create a .PBL (pronounced 'pebble') in your drive A. Name the .PBL - myfirst. myfirst.pbl is simply a DOS file that can hold many PowerBuilder objects.

Step 2: Create an application object

Create a new application named basic using the application painter. When PB starts, it always connects to the last used application. Start the application painter and choose "NEW" from the FILE menu. 'SELECT NEW APPLICATION LIBRARY" dialog displays. Choose myfirst.pbl as the file name. Here you are specifying that your new application object be saved in myfirst.pbl. SAVE APPLICATION AS dialog displays, name your new application as basic. From the EDIT,LIBRARY LIST menu item ensure that the application search path is specified as myfrst.pbl.

GO TO TOP

Step 3: Create a Window

Create a window called w_first using the window painter. Ensure you save this in myfirst.pbl. Now, you myfirst.pbl has two objects: an application object, and a window object. Objects and controls have events associated with them. You can write powerscript programming language to write scripts in various events. Place a command button called CLOSE (When you type in the name, type &Close - this will make Alt-C the shortcut key at run time) in this window and write the script:

in the clicked event of this command button. The parent of this command button is the window that contains it. Hence, this script simply means that you want the window closed when you click on the CLOSE command button.

Step 4: Add a script to the application open event

Now, you can go to the application open event and specify

Step 5: Run the application

Run the application using the running man icon, and observe its behavior.

GO TO TOP

CONNECT TO A DATABASE AND PERFORM A SIMPLE RETRIEVAL

• Learn how a simple datawindow object is created
• Understand the role of a datawindow control in a window object
• Learn to attach a datawindow object to a datawindow control
• Learn the basics of creating and using SQLCA, the default transaction object.
• Learn to perform a simple database retrieval.

The power of PB lies in its ability to access relational databases. PowerBuilder provides a special control, called datawindow control to perform this task. The datawindow control is a container for datawindow object which actually provides the link to databases. We first create a datawindow object, then attach the datawindow object to a datawindow control that is contained in a window.

Step 6: Create a datawindow object

Using the datawindow painter, you wil now create a new datawindow object. After you launch the datawindow painter, you will asked to specify a datasource and a presentation style. Select the datasource to be SQL SELECT and the presentation style to be tabular. Select a table from the SELECT TABLES dialog, click on the columns that you want to view from this table (you can see the SQL statements generated by clicking on the Syntax tab on the tab folder at the bottom.) Go to the design mode and click on "preview" painter bar button and ensure that the data is properly retrieved. Save the datawindow as d_first. If you go to your library painter, you will see that your application now has three objects: basic, an application object; w_first, a window object, and d_first, a datawindow object.

Step 7: Attach datawindow object to datawindow control

Open your window object by double clicking on your library entry, and place a datawindow control on this window. Although this appears in its default size when you initially place it, you can grab the cornor or the sides of the control to resize it within the window. Double click on the datawindow control, Select DataWindow dialog appears. Attach d_first to this datawindow control. After you attach, the column headings of your datawindow object should be clearly visible within the control. If not, you can again resize the control appropriately (you would not see any data in the control until you write few lines of code (referred to powerscripts by PB,) and run the application.

GO TO TOP

Step 8: Add script in the application open event to connect to database

Type in the following code in your application open event - before opening w_first:

Step 9: Add script in the window open event to retrieve data

In the open event of w_first type in the script

and run the application.

GO TO TOP

Please send your comments to: Raghavan

© Dr. Vijay V. Raghavan

BACK TO Table of contents

BACK TO DATABASE Main Page