Click here to close now.

Welcome!

.NET Authors: Liz McMillan, Carmen Gonzalez, Elizabeth White, Greg O'Connor, Jason Bloomberg

Related Topics: PowerBuilder, .NET

PowerBuilder: Article

Automating Your DataWindow

The IF function, green bar DataWindows, conditional properties

Every programmer knows about the IF command. It's pretty much a fundamental part of the syntax of every computer language that has ever existed. I don't need to explain how it works.

The DataWindow can't use the IF command though. It does, however, support an IF function.

IF(expression, TRUE, FALSE)

In its simplest form this means that if the expression evaluates to TRUE, then whatever statement you supply for the TRUE part is executed. If not then the FALSE part is.

Let's begin with a simple example. Let's create a DataWindow that will show employee information. Here is the SQL for it:

SELECT employee_a.emp_id,  
employee_a.manager_id,  
employee_b.emp_fname manager_first_name,  
employee_b.emp_lname manager_last_name,  
employee_a.emp_fname employee_first_name,  
employee_a.emp_lname employee_last_name,  
department.dept_name,

employee_a.status,  
employee_a.salary 
FROM employee employee_a,  
employee employee_b,  
department 
WHERE ( employee_a.dept_id = department.dept_id ) and 
( employee_a.manager_id = employee_b.emp_id )  
ORDER BY department.dept_name ASC,  
employee_a.emp_lname ASC,  
employee_a.emp_fname ASC

We will use this to show employee information and to show the manager's name of the employee (that's the employee_b part. Also notice that I named the employee and manager names so that I won't get confused when I get back to the DataWindow painter.

Also notice that I am sorting first by department name then the name of the employee. The reason for this will become obvious later.

Let's Start with a Green Bar
We have a lot to work with here. First there will be quite a few rows. When you have a lot of rows it becomes hard to keep your eye on one row as you go across the screen. It's easy to make mistakes. Green bar paper was meant to help that. Green bar paper is paper that has green bars printed across it. Those green bars help the eye stay on whatever row it's seeing.

In other words, green bar paper helps the reader keep on the same line.

That could come in handy for us. We don't have to use green for the color and in fact I've always liked to use a pale yellow. That way the color doesn't get in the way of the text. We can still use colors for the text and use the yellow to line up the data.

We create our DataWindow using the SQL given above. The first thing that I do is delete everything from the surface of the DataWindow. A Ctrl-A (for all) and then the delete key handles that quite nicely.

Now for the Pale Yellow
We need a custom color. The lightest of the yellows is not pale enough. Colors are defined by Red, Green, and Blue. Each of the colors can be a value of 0 (complete lack) to 255 (brightest). If you want a bright red that would be 255, 0, 0. If you want white that would be 255, 255, 255. Black would be 0, 0, 0. All of the dark colors would be half of 255.

If you think about it you can come up with a lot of different shades. Since yellow is red and green we want full red, full green, and 75% blue. That would be 255 * .75 or 191. There's no need to be concerned with fractions here.

Go to Design in the menu then select Custom Colors.

Notice where the figure says to click there first. That way you define where your custom color goes. Once you've selected that go over to the right and type in your values for red, green, and blue. Now you have a custom color that you can use forever. Of course you can change that color any time but since you have 16 custom colors you can probably have all your favorites there.

Back to the DataWindow
Okay, now we have a DataWindow from which we have deleted everything. To do the green bar we need a rectangle object. Simply place it on the screen and stretch it out to be as long as you think the row will be. Set the foreground and background colors to be your new pale yellow custom color. Make sure that the rectangle is taller than your row will be. You will eventually slide the detail band up to cover it.

Take a look at Figure 2. You should move the rectangle as close to the top of the detail band as you can. Here's a hint. Select the rectangle by clicking on it. Drag it all the way to the left. Then, using the up arrow, move it toward the top of the detail band one keystroke at a time. Eventually you will hit the up arrow and the rectangle will vanish. It has gone into the header band. Hit a down arrow and it comes back. It will then be as close to the top as possible.

Figure 2 points out that you should leave some space between the bottom of the rectangle and the detail band. We will move the detail band up later, making the rectangle neatly fill the entire detail area.

The next step is to implement the green bar. What we will do is have the rectangle be invisible on every other line. It really doesn't matter whether the rectangle is visible on the even or odd lines. I guess it's a matter of choice. Personally, if we are going to have column headers I like to start with the rectangle. That way we don't have a large white area at the top.

Again, it doesn't really matter though.

How do we do this? We find the visible property of the rectangle. If that property is 1, then the rectangle is visible. If it is 0 then it's not.

That means that we need the IF function. It needs to be:

IF(odd_row, 1, 0)

That's not so bad. If the row is an odd number, set the visible property to 1, otherwise to 0.

The next question is how in the world do we find out if the row is odd? Well, there is a function that we can use called Mod(x, y). The x is the number that you want to divide by y. The y is the number you want to divide into x. Mod will return the remainder of the operation.

For example, mod(13, 4) will return 1. 13 / 4 = 3 with a remainder of 1.

If we can know the current row we can use a mod(currentRow(), 2). If this returns a 1, the row is odd. Otherwise it's even.

Figure 3 shows you the properties for the selected rectangle. You can see that the Visible property is circled. See the little button to the right of it? Whenever you see one of those the property can have an expression. Click on that button.

Now look at Figure 4. It shows the dialog that you use to create your expressions. Notice that we are setting the expression for the rectangle. I also wanted to point to the list of available functions. You can see the CurrentRow() function in the list of functions. In our case I am showing you where I got it. The Mod function (which I also used) is farther down in the list but it's there.

Over to the bottom right you can see a list of all of the columns in the DataWindow. If we wanted to we could make the visibility of the rectangle dependent on the value of one of the columns. For example, we could have said:

if(employee_status = 'L', 1, 0)

In that case the rectangle would only be visible for every employee that was on leave. In fact, since there are three possible statuses of each employee we could have three different rectangles, each with a different color and set each dependent on the status. That way our DataWindow would show a different background for each status.

Let's not do that though.

What we did was to use a function that would allow us to turn on the rectangle for odd numbered rows and turn it back off for even rows. Let's look at that expression:

if(mod(getrow(), 2) = 0, 0, 1)

The getRow provides us with the current row. The mod function will return the remainder of the getRow() / 2. Thus, for row 1 we will get:

if(mod(1, 2) = 0, 0, 1

for row 2 we will get:

if(mod(2,2) = 0, 0, 1)

This will result in us getting a visible rectangle for every other row. That's exactly what we wanted. Now we can populate our DataWindow with the columns that we want in the order that we want. I really like using computed fields for columns that I don't intend the user to change, especially names. So my first column will be the user name. I set that up as a computed field.

employee_employee_last_name + ', ' +  employee_employee_first_name

Now the name will be properly formatted (see Figure 5).

That looks a lot better than putting the two names on the DataWindow and having a variable space between the first and last.

Now let's put the manager on the DataWindow. The expression for that would be:

'Manager: ' +  employee_manager_last_name + ', ' +  employee_manager_first_name

Let's use the status of the employee. If the employee is terminated let's make their name red. If they are on leave, let's make them gray. If they are active, let's leave it black.

To do this we need to do an expression for the foreground color of the name computed field. Select that computed field then in the properties find the foreground color. In case you are having problems I will provide help (see Figure 6).

The expression for that will be a lot more complex. We will need to use another function called RGB.

The RGB function takes three arguments, each of which are integers from 0-255. They are, in order, Red, Green, and Blue.

Here will be the expression. I know it looks complicated but don't worry, we'll take it apart.

if( employee_status = 'A', 0, if( employee_status = 'L', RGB(127,127,127), RGB(255,0,0)))

This says, if the employee status is A (active) then the color will be 0. That would be black. The FALSE part of the IF function is another IF function. This one says that if the employee status is L, the color needs to be 127,127,127. That means each of the colors is only half bright. This gives us gray. Otherwise, if the employee status is anything other than A or L, it should be bright red.

That's all there is to it. This will serve us very well.

There's usually more than one way.

We could make this easier to code and easier to maintain. Expressions can use global functions so we could write a function like the following:

Long f_status_color(string as_status)
choose case UPPER(as_status)
case "A"
return 0
case "L"
return RGB(127, 127, 127)
case else
return  RGB(255, 0, 0)
END CHOOSE

Then replace that complex if function with the following:

f_status_color( employee_status )

That is so much easier. The only down-side is that if you make a habit of this, you wind up with a lot of functions. Of course you could put them all in their own PBL and they would be out of the way.

Are we done yet?

Well, not really. We haven't done anything with the department. We have sorted by the department so let's create a control break on the department.

Control Break is what we called a Group back in the days when I went to college. Select Rows and Create Group from the menu, then drag the Department Name over to the Columns as in shown in Figure 7.

Now all we have to do is throw the DataWindow into a window, add two lines, one to set the transaction object and the other to set retrieve the DataWindow and we are done (seem Figure 8). Most of the functionality is inside the DataWindow, right where it should be.

More Stories By Richard (Rik) Brooks

Rik Brooks has been programming in PowerBuilder since the final beta release before version 1. He has authored or co-authored five books on PowerBuilder including “The Definitive DataWindow”. Currently he lives in Mississippi and works in Memphis, Tennessee.

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


@ThingsExpo Stories
The Internet of Things Maturity Model (IoTMM) is a qualitative method to gauge the growth and increasing impact of IoT capabilities in an IT environment from both a business and technology perspective. In his session at @ThingsExpo, Tony Shan will first scan the IoT landscape and investigate the major challenges and barriers. The key areas of consideration are identified to get started with IoT journey. He will then pinpoint the need of a tool for effective IoT adoption and implementation, which leads to IoTMM in which five maturity levels are defined: Advanced, Dynamic, Optimized, Primitive,...
SYS-CON Events announced today that AIC, a leading provider of OEM/ODM server and storage solutions, will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. AIC is a leading provider of both standard OTS, off-the-shelf, and OEM/ODM server and storage solutions. With expert in-house design capabilities, validation, manufacturing and production, AIC's broad selection of products are highly flexible and are configurable to any form factor or custom configuration. AIC leads the industry with nearly 20 years of ...
SYS-CON Events announced today that Vicom Computer Services, Inc., a provider of technology and service solutions, will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. They are located at booth #427. Vicom Computer Services, Inc. is a progressive leader in the technology industry for over 30 years. Headquartered in the NY Metropolitan area. Vicom provides products and services based on today’s requirements around Unified Networks, Cloud Computing strategies, Virtualization around Software defined Data Ce...
How is unified communications transforming the way businesses operate? In his session at WebRTC Summit, Arvind Rangarajan, Director of Product Marketing at BroadSoft, will discuss how to extend unified communications experience outside the enterprise through WebRTC. He will also review use cases across different industry verticals. Arvind Rangarajan is Director, Product Marketing at BroadSoft. He has over 19 years of experience in the telecommunications industry in various roles such as Software Development, Product Management and Product Marketing, applied across Wireless, Unified Communic...
As we approach the next @ThingsExpo, to be held June 9-11 at the Javits Center in New York, my thoughts naturally turn to the Internet of Things. The IoT is a leviathan—in the best possible sense of the term—that will sweep up most everything in the ocean of data and technology being created today and tomorrow. But rather than try to grasp all of its possible uses, for today I'm looking at “just” the Industrial Internet part. I just read a long paper co-authored by Tim Berners-Lee about the possibility of describing a “web science,” that is, discipline that combines the study involved ...
The best mobile applications are augmented by dedicated servers, the Internet and Cloud services. Mobile developers should focus on one thing: writing the next socially disruptive viral app. Thanks to the cloud, they can focus on the overall solution, not the underlying plumbing. From iOS to Android and Windows, developers can leverage cloud services to create a common cross-platform backend to persist user settings, app data, broadcast notifications, run jobs, etc. This session provides a high level technical overview of many cloud services available to mobile app developers, includi...
Enterprise IoT is an exciting and chaotic space with a lot of potential to transform how the enterprise resources are managed. In his session at @ThingsExpo, Hari Srinivasan, Sr Product Manager at Cisco, will describe the challenges in enabling mass adoption of IoT, and share perspectives and insights on architectures/standards/protocols that are necessary to build a healthy ecosystem and lay the foundation to for a wide variety of exciting IoT use cases in the years to come.
The IoT Bootcamp is coming to Cloud Expo | @ThingsExpo on June 9-10 at the Javits Center in New York. Instructor. Registration is now available at http://iotbootcamp.sys-con.com/ Instructor Janakiram MSV previously taught the famously successful Multi-Cloud Bootcamp at Cloud Expo | @ThingsExpo in November in Santa Clara. Now he is expanding the focus to Janakiram is the founder and CTO of Get Cloud Ready Consulting, a niche Cloud Migration and Cloud Operations firm that recently got acquired by Aditi Technologies. He is a Microsoft Regional Director for Hyderabad, India, and one of the f...
SYS-CON Events announced today that B2Cloud, a provider of enterprise resource planning software, will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. B2cloud develops the software you need. They have the ideal tools to help you work with your clients. B2Cloud’s main solutions include AGIS – ERP, CLOHC, AGIS – Invoice, and IZUM
SYS-CON Events announced today that MangoApps will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY., and the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. MangoApps provides private all-in-one social intranets allowing workers to securely collaborate from anywhere in the world and from any device. Social, mobile, and easy to use. MangoApps has been named a "Market Leader" by Ovum Research and a "Cool Vendor" by Gartner...
SYS-CON Media announced today that @ThingsExpo Blog launched with 7,788 original stories. @ThingsExpo Blog offers top articles, news stories, and blog posts from the world's well-known experts and guarantees better exposure for its authors than any other publication. @ThingsExpo Blog can be bookmarked. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago.
The world's leading Cloud event, Cloud Expo has launched Microservices Journal on the SYS-CON.com portal, featuring over 19,000 original articles, news stories, features, and blog entries. DevOps Journal is focused on this critical enterprise IT topic in the world of cloud computing. Microservices Journal offers top articles, news stories, and blog posts from the world's well-known experts and guarantees better exposure for its authors than any other publication. Follow new article posts on Twitter at @MicroservicesE
SYS-CON Events announced today that robomq.io will exhibit at SYS-CON's @ThingsExpo, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. robomq.io is an interoperable and composable platform that connects any device to any application. It helps systems integrators and the solution providers build new and innovative products and service for industries requiring monitoring or intelligence from devices and sensors.
Wearable technology was dominant at this year’s International Consumer Electronics Show (CES) , and MWC was no exception to this trend. New versions of favorites, such as the Samsung Gear (three new products were released: the Gear 2, the Gear 2 Neo and the Gear Fit), shared the limelight with new wearables like Pebble Time Steel (the new premium version of the company’s previously released smartwatch) and the LG Watch Urbane. The most dramatic difference at MWC was an emphasis on presenting wearables as fashion accessories and moving away from the original clunky technology associated with t...
SYS-CON Events announced today that Litmus Automation will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Litmus Automation’s vision is to provide a solution for companies that are in a rush to embrace the disruptive Internet of Things technology and leverage it for real business challenges. Litmus Automation simplifies the complexity of connected devices applications with Loop, a secure and scalable cloud platform.
As Marc Andreessen says software is eating the world. Everything is rapidly moving toward being software-defined – from our phones and cars through our washing machines to the datacenter. However, there are larger challenges when implementing software defined on a larger scale - when building software defined infrastructure. In his session at 16th Cloud Expo, Boyan Ivanov, CEO of StorPool, will provide some practical insights on what, how and why when implementing "software-defined" in the datacenter.
There is no doubt that Big Data is here and getting bigger every day. Building a Big Data infrastructure today is no easy task. There are an enormous number of choices for database engines and technologies. To make things even more challenging, requirements are getting more sophisticated, and the standard paradigm of supporting historical analytics queries is often just one facet of what is needed. As Big Data growth continues, organizations are demanding real-time access to data, allowing immediate and actionable interpretation of events as they happen. Another aspect concerns how to deliver ...
So I guess we’ve officially entered a new era of lean and mean. I say this with the announcement of Ubuntu Snappy Core, “designed for lightweight cloud container hosts running Docker and for smart devices,” according to Canonical. “Snappy Ubuntu Core is the smallest Ubuntu available, designed for security and efficiency in devices or on the cloud.” This first version of Snappy Ubuntu Core features secure app containment and Docker 1.6 (1.5 in main release), is available on public clouds, and for ARM and x86 devices on several IoT boards. It’s a Trend! This announcement comes just as...
WebRTC defines no default signaling protocol, causing fragmentation between WebRTC silos. SIP and XMPP provide possibilities, but come with considerable complexity and are not designed for use in a web environment. In his session at @ThingsExpo, Matthew Hodgson, technical co-founder of the Matrix.org, discussed how Matrix is a new non-profit Open Source Project that defines both a new HTTP-based standard for VoIP & IM signaling and provides reference implementations.
The security devil is always in the details of the attack: the ones you've endured, the ones you prepare yourself to fend off, and the ones that, you fear, will catch you completely unaware and defenseless. The Internet of Things (IoT) is nothing if not an endless proliferation of details. It's the vision of a world in which continuous Internet connectivity and addressability is embedded into a growing range of human artifacts, into the natural world, and even into our smartphones, appliances, and physical persons. In the IoT vision, every new "thing" - sensor, actuator, data source, data con...