Using crosstabs
To perform certain kinds of data analysis, you might want
to design DataWindow objects in the Crosstab presentation style.
The basic steps for using crosstabs in an application are the same
ones you follow for the other DataWindow types, but there are some
additional topics concerning crosstabs that you should know about.
To learn about designing crosstabs, see the PowerBuilder
User’s Guide
.
Viewing the underlying data
If you want users to be able to see the raw data as well as
the cross-tabulated data, you can do one of two things:
- Place two DataWindow controls on the window or form:
one that is associated with the crosstab and one that is associated
with a DataWindow object that displays the retrieved rows. - Create a composite DataWindow object that contains
two reports: one that shows the raw data and one that shows the
crosstab.
Do not share data between the two DataWindow objects
or reports They have the same SQL SELECT data definition, but they have
different result sets.
For more about composite DataWindows, see
the PowerBuilder User’s Guide
.
Letting users redefine the crosstab
Availability This technique is available in PowerBuilder and the Web ActiveX.
With the CrosstabDialog method, you can allow users to redefine
which columns in the retrieved data are associated with the crosstab’s
columns, rows, and values during execution.
The CrossTabDialog method displays the Crosstab Definition
dialog box for the user to define the data for the crosstab’s
columns, rows, and values (using the same techniques you use in
the DataWindow painter). When the user clicks OK in the dialog box,
the DataWindow control rebuilds the crosstab with the new specifications.
Displaying informational messages
You can display informational messages when a crosstab is
rebuilt during execution as a result of the call to CrosstabDialog.
(The messages are the same ones you see when building a crosstab
in the DataWindow painter, such as Retrieving
data and Building crosstab.)
You might want to do this if you are working with a very large number
of rows and rebuilding the crosstab could take a long time.
PowerBuilder In PowerBuilder, you use a user event to display the crosstab’s informational
messages.
To display informational messages when a crosstab
is rebuilt:
-
Define a user event for the DataWindow
control containing the crosstab. Associate it with the event ID
pbm_dwnmessagetext. -
In
the script for the user event, get the value of the text argument
(which holds the message that PowerBuilder would display when building
the crosstab in the DataWindow painter) and display it to the user.
Web ActiveX In a Web page, you use the DataWindow’s onMessageText event
to handle informational messages.
To display informational messages when a crosstab
is rebuilt:
-
Edit the code for the onMessageText event
of your DataWindow control. -
In that event, get the value of the Text argument
and display it to the user.
Examples
PowerBuilder In the example, code for the DataWindow control’s
user event for pbm_dwnmessagetext displays informational
messages in a static text control in the window containing the crosstab:
|
1 |
st_message.Text = text |
With that script in place, after CrosstabDialog has been called
and the user has redefined the crosstab, as the crosstab is being
rebuilt, your application dynamically displays the informational
messages in the static text control st_message. (You might
want to reset st_message.Text to be the empty string in
the line following the CrosstabDialog call.)
In this example, code in the user event for pbm_dwnmessagetext
displays informational messages as MicroHelp in an MDI application
(w_crosstab is an MDI frame window):
|
1 |
w_crosstab.SetMicroHelp(text) |
The informational messages are displayed in the MDI application’s
MicroHelp as the crosstab is rebuilt.
For more information
For more about user events in PowerBuilder, see the PowerBuilder
User’s Guide
.
For more about the CrosstabDialog method and MessageText event,
see the DataWindow Reference
.
Modifying the crosstab’s properties during
execution
As with other DataWindow objects, you can modify the properties
of a crosstab during execution using the Modify method. Some changes
require the DataWindow control to dynamically rebuild the crosstab;
others do not. (If the original crosstab was static, it becomes
a dynamic crosstab when it is rebuilt.)
Availability You can use this technique in all DataWindow environments.
Changes that do not force a rebuild
You can change the following properties without forcing the
DataWindow control to rebuild the crosstab:
| Properties | Objects |
|---|---|
| Alignment | Column, Compute, Text |
| Background | Column, Compute, Line, Oval, Rectangle, RoundRectangle, Text |
| Border | Column, Compute, Text |
| Brush | Line, Oval, Rectangle, RoundRectangle |
| Color | Column, Compute, Text |
| Edit styles (dddw, ddlb, checkbox, edit, editmask, radiobutton) |
Column |
| Font | Column, Compute, Text |
| Format | Column, Compute |
| Pen | Line, Oval, Rectangle, RoundRectangle |
| Pointer | Column, Compute, Line, Oval, Rectangle, RoundRectangle, Text |
Changes that force a rebuild
If you change any other properties, the DataWindow control
rebuilds the structure of the crosstab when Modify is called. You
should combine all needed expressions into one Modify call so that
the DataWindow control has to rebuild the crosstab only once.
Default values for properties
For computations derived from existing columns, the DataWindow
control by default uses the properties from the existing columns.
For completely new columns, properties (such as font, color, and
so on) default to the first column of the preexisting crosstab.
Properties for text in headers default to the properties of the
first text control in the preexisting crosstab’s first
header line.
For more about the Modify method, see Chapter 3, “Dynamically Changing DataWindow
Objects .” For details
on the DataWindow object properties, see the DataWindow
Reference
.