A Complex, Powerful Paradox
Paradox for Windows, the new version of Borland International’s powerful relational database system, is packed with features that make it a strong contender for development of heavy-duty database applications.
It retains some of the flavor of the DOS versions of Paradox, particularly the well-regarded “query by example” function for defining what information you want to retrieve from a database. But it has lost the simplicity of the command menus that make it fairly easy, in the DOS version, for casual users to create basic databases.
On the other hand, learning how to use the programming language of Paradox for Windows, ObjectPAL, may be easier than for the DOS version because it can be done incrementally. You can manipulate the way a database application behaves as little or as much as you like by adding corresponding amounts of programming code.
Borland is offering Paradox for Windows at an introductory price of $140 through April 30. Thereafter its suggested retail price is $795--about $300 more than the suggested retail price Microsoft has set for its new Access database program.
Compared to the new Microsoft Access database program, Paradox for Windows seems a little less user-friendly, and the logic of its design is harder to discern.
For instance, a common requirement in database applications is to assign unique sequential identification numbers to customers, employees, vendors, and parts. Microsoft Access provides a simple way to do that with a special type of data field called a counter.
Paradox for Windows has no such field. You have to write a complicated programming statement to accomplish the same thing. (An example is shown in one of the manuals.) Furthermore, you don’t apply the programming code where you think it would logically belong, in the same place you define the structure of the data field that will store the ID number.
On the other hand, Paradox for Windows has some features that Access lacks. For instance, it can store formatted text of virtually unlimited length in a special memo field associated with each record of data. That means memos can have various sizes and styles of fonts and take on a typeset quality.
What good is that? Paradox for Windows could be used as a tool to print customized textbooks or reports tailored to readers based on various data about them--their buying preferences, for instance.
The program has some other unusual and useful field types, such as graphics for pictures and BLOBs, which stands for “binary large objects.” The latter can include sound files or digitized video or animations. Borland’s new program has many powerful features that were designed for use in elaborate, company-wide database applications.
One is called referential integrity. It prevents data that is related to other data from being added or deleted accidentally. For instance, a sale could not be recorded to a customer for whom a customer record did not exist in the database. Conversely, the customer record could not be deleted unless all traces of that customer’s transactions were first removed.
Password control can be applied to individual fields in a data table. A clerk could be allowed to change an employee’s address, but not add or delete employees on the payroll, for instance.
Although Paradox for Windows can work directly with existing data tables created both by recent DOS versions of Paradox and by dBASE, its full power is available only with its own Paradox for Windows data files.
The program is designed for use on computer networks, but the ability to connect to external database files with the SQL command language is not included. That will be a separate companion product, scheduled for delivery this summer.
“Query by example” has been a popular feature of previous versions of Paradox and it is included in Paradox for Windows in largely the same form. In simple terms, you can retrieve what you want from a database simply by putting a computerized check mark on the fields to be examined and displayed and then typing in an example of the kind of data you want to see.
If you wanted to contact all California customers who ordered a particular product, you could enter “CA” as a query example in the state field and the product name in the product field.
Queries like that can actually be made part of a report, making it easier to automate repetitive data-reporting tasks.
Aside from its use of the Windows graphical user interface, a major distinction between Paradox for Windows and Paradox DOS versions is that everything in the Windows version is an “object” with characteristics that can be defined independently of other aspects of the program.
So-called object-oriented programming is the latest technique in computer programming, and Paradox for Windows serves as a good introduction to the concept for someone with the time and patience to learn how to make use of it.
In the most simple form, the “properties” of an object that can be easily altered by the user can be called to the screen in a special menu by pressing the right-side mouse button. Further menu choices make the alterations. More elaborate changes to properties and behavior of program objects, such as individual fields in a report or a form, can be controlled through the use of the ObjectPAL programming language.
Overall, this is a complex and somewhat difficult program to grasp, but it has a lot of power for the user with the need for that power and the willingness to persevere long enough to achieve competence using it.
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