Have you ever seen a form that has its own microhelp that changes when a
field gets focus? I'm sure you have. You might see a window and at the bottom
of the window is a line that says, "OPTIONAL - Enter the employee birth
date," when a field is entered. We are going to create a simple automated
solution that will allow you to carry the microhelp along in the DataWindow.
Take a look at Figure 1. It's a freeform DataWindow with a SQL data source. I
chose the Employee table from the sample database that comes with
PowerBuilder. I didn't do anything special to it. My goal here is to show you
how to automate a microhelp. When PowerBuilder put the columns on the
DataWindow painter, the tab was automatically set. I just left it at the
Then I created a window and threw the DataWindow into it. I threw a custom
object on the window and associated it with the DataWi... (more)
This article provides a means of automating the sorting of DataWindows... not
just grid DataWindows as discussed in last month's article, but all
DataWindows, regardless of display format.
Bear in mind that we are writing programmer tools. When writing for
programmers we want to give the programmer the maximum number of options
while minimizing the programmer effort. In other words, default as much as
possible but allow the programmer to move beyond the defaults.
We have several action items to implement:
Do the housekeeping to get an application going Create a window for sorting.... (more)
Security is a must for most corporate applications. This article will give
you a starting point to designing and implementing your own. We will do it
with a table that is added to the example database and implement it in
ancestor code. The idea is that you should only have to add rows to a table
to implement your security.
The security table will provide a means to turn on and off controls and menu
items as our inherited objects are constructed.
Login_name varchar(20) PK
Application varchar(20) PK
Item_type varchar(10) PK
Item_name varchar(20) PK
Priviledge ... (more)
One of the most useful custom objects that I've ever written is my
master_detail object. It holds a prominent place in my toolkit. This article
will take you through the steps of how to write one and in the process
de-mystify the object.
First we want something that looks like Figure 1. Selecting a row in the top
DataWindow will display the details in the bottom. I'm sure that you've seen
this kind of DataWindow and you've probably written many of them. The key
here is not to tell you how to write this but how to simplify every one that
you will write in the future. For our exam... (more)
Have you ever used a datastore that ran without a problem while you were
developing your application, but once you've compiled it stopped running? Let
me tell you that's a difficult bug to fix.
I remember it so well. I kept going back and forth. How in the world could
the DataWindow work at design time yet not in the executable? I remember that
I checked the return value of the datastore. I finally noticed that the
datastore returned a -1. That's such a strange thing.
The datastore returns the number of rows that were returned or a -1. The help
files used to say that a -1 was in ... (more)