The Definition of .dbf

In the early 1980s, pioneering personal computer software maker Ashton-Tate released a program called dBase II, the first database manager for microcomputers. DBase II had its own programming language and used .dbf files containing user-definable fields for character, number and date information. By building custom .dbf files and writing programs in dBase II, software developers created custom accounting and management software applications for small to medium-sized businesses.

1. DBase

   • Ashton-Tate originally offered dBase II for early non-IBM PC operating systems such as CP/M, then released a version for MS-DOS when IBM introduced their first PC. DBase was a standalone programming and database environment in which a developer wrote programs in the dBase language, and stored them in files with the extension .prg. These files contained dBase commands that opened, displayed, processed and printed the data in .dbf, or DBF, files. Each .dbf file acted as a table of information organized into fields. For example, a customer.dbf might contain customer records, each of which consists of fields such as customer code, name, address and telephone number. DBase allowed for automated data selection and sorting, features previously available only on high-end computer systems.

   DBF File Format

   • Dbase organized DBF files into two main parts: a descriptive header at the beginning of the file followed by the record data itself. The header consisted of a version number, the date the file was last updated and a record count, followed by other information including a variable-length array containing the record structure. The record structure contained field names, data types and sizes. In a customer .dbf file, for example, the actual customer name and address data followed the header information.

   Index Files

   • The use of separate .ndx files allowed dBase to create high-speed field indexes for files. To find a customer in a customer file, for example, the program could read through the file record by record until it found the right one, but this would be very time-consuming for many tasks. DBase allowed a programmer to designate one or more index fields which a program would use as a high-speed, direct lookup for specific records. If she created an index file from the customer code field, a program would look in the index file for a particular customer code and dBase would locate the correct record in a fraction of a second.

   Xbase

   • Dbase’s popularity and versatility inspired other software developers to create compatible products that used its .dbf files but offered features not found in Ashton-Tate’s software. These products turned the dBase environment into a more generic industry standard dubbed Xbase. Clipper, for example, provided a compiler program that turned .prg files into executable .exe files. Software developers preferred this, as they could distribute the .exe and .dbf files to clients without the development software; before this, all users had to purchase a copy of dBase to run any application developed with it. Foxbase, later becoming Microsoft’s Visual FoxPro, had a sophisticated user interface including windows with buttons and drop-down menus.