dBASE has been around for years—it’s even older than the PC itself—and millions of lines of dBASE code have produced tens of thousands of applications over the years. The dBASE architecture has been used as a basis for numerous lookalike products (generically referred to as Xbase products), several of which have surpassed dBASE in speed and features.
When Borland acquired Ashton-Tate, many of us wondered if dBASE was dead, with pieces of the carcass to reappear in other Borland products. Our review of dBASE IV, Version 2.0, shows that dBASE is alive and well. Version 2.0, which will be shipping by the time you read this, brings with it some sorely needed performance enhancements. In addition, Borland has rolled out a new compiler, the dBASE Compiler for DOS. which should make dBASE even more attractive to developers.
dBASE IV was one of the first database products to gather together the elements of a database into a central location (what dBASE dubs the Control Center) where you can directly access any data table, query, form, report, label, or program procedure in your application. Despite the character-based DOS interface, you can draw forms or reports on the screen and let dBASE create the underlying code. Behind the scenes is a flexible programming language with the power to create substantial multiuser applications.
The new speed demon
One of the major problems of dBASE IV was lack of speed; in recent years clone products have run rings around it. Borland’s Version 2.0 release breathes new life into this venerable workhorse by concentrating on performance. At the same time, it offers some new functionality to developers and a faster, more user-friendly installation program.
dBASE now benefits from Borland’s index algorithm technology, which provides substantial speed improvement by itself. However, the most significant improvement is that dBASE now uses indexes wherever possible. In the past, a ‘SET FILTER TO. . .’ operation would ignore existing indexes and plod through a file record by record; now it uses available indexes to zip through filtered files.
The use of indexes is extended to any operation involving a ‘FOR’ condition, speeding up a large majority of common operations. QBE also benefits. If you narrow your filter with another AND condition. dBASE will start from the previous result set rather than starting over as in the previous version.
These changes, along with other improvements such as the DPMI-compliant use of extended memory, can make dBASE applications many times faster than before. While we were unable to include dBASE IV 2.0 in our formal benchmarks, we ran a late beta version through the performance test suite. True to Borland’s promotional claims, dBASE IV 2.0 is speedy. It scored well across the test suite and beat all the Xbase languages on writes to a full-loaded network. With scores of one and two seconds on the numeric and alphanumeric selection test, dBASE IV came in only a fraction of a second behind the Microsoft FoxPro products.
Version 2.0 contains a few enhancements to the programming language, particularly in the area of user interface design. Although earlierversions of dBASE IV recognised a mouse, until now you couldn’t incorporate a mouse into your application’s user interface. New commands such as ON MOUSE recognise the user’s click of the left mouse button, and the MR0W() and MCOLO functions tell your program the mouse’s current screen location. In addition, you can now program mouse-driven radio buttons, check boxes, and check lists into the applications you develop.
Other functions have also been added or enhanced: The KEYMATCH() function checks to see if an expression is found in a specified index; the TIME() function can return the time to hundredths of seconds; and the MEMORYf) function returns details about dBASE’s memory utilisation.
Error trapping is also improved. dBASE can now detect when the disk is full or damaged or when a file is missing. The debugger lets you set breakpoints using Ctrl-T and execute the currently highlighted command with Ctrl-L. These and some navigation keystroke enhancements make the debugger more usable, though it is still not perfect.
A compiler, then Windows
The dBASE Compiler for DOS ($795) was released at the same time as the new dBASE IV. Compatible with all versions of dBASE III PLUS and dBASE IV, the compiler builds .EXE files in two optional models. One model incorporates the library functions; the other compiles to a smaller .EXE and makes calls to a runtime library. End users can run the standalone executables without any additional dBASE system files, and developers can distribute .EXEs free of licensing fees.
A Windows version of dBASE IV, which will share the same engine as Borland’s Paradox for Windows, is in the works. Originally slated as a compiler-only product, Borland has decided to include screen design and end-user tools in the initial release, which has pushed the release date to the end of the year at the earliest.
All in all, this new version is the shot in the arm dBASE IV has needed for years. The improved performance, especially in multiuser environments where large databases are the norm, will make it a hit with current dBASE shops and should win over customers who were considering going elsewhere.
Requires: 286-based PC or better, 2M RAM, DOS 3.3 or later.
