The information in this article applies to:
SUMMARY
Moderate: Requires basic macro, coding, and interoperability skills.
MORE INFORMATION
There are seven available .DDF files: FILE.DDF, FIELD.DDF, INDEX.DDF,
ATTRIB.DDF, VIEW.DDF, USER.DDF, and RIGHTS.DDF. Microsoft Access version
2.0 requires only FILE.DDF and FIELD.DDF. Microsoft Access can maintain the
INDEX.DDF file for interoperability with Xtrieve, but the default is not to
maintain it.
Each Btrieve database file (.DAT file) contains only one table. Therefore, a Btrieve application may have several .DAT files File DefinitionsFILE.DDF:The FILE.DDF file contains the following elements:
The sample FILE.DDF file above indicates that the FILE.DDF, FIELD.DDF, and INDEX.DDF files (file numbers 1, 2, and 3) are in the directory C:\MYDIR. The entry in the Xf$Flags column (16) indicates that these files are system files that are used to locate other system files. NOTE: Xtrieve uses the paths listed in the FILE.DDF file to search for these system files. Microsoft Access, however, only looks for these files in the same directory where the FILE.DDF file was found. File numbers 4, 5, and 6 contain information on three Btrieve database files that can be used by Microsoft Access as attached tables. The entry in the Xf$Flags column (0) indicates that these are user-defined files. File number 4, TestFile, does not have a path specified. Therefore, Microsoft Access will search for this file in the directory in which it found the FILE.DDF file. File number 5, DataFile, has a drive and path specified. Microsoft Access will search the specified drive and path for the file. File number 6, MyData, has a path but no drive specified. Microsoft Access will search for this file in the MOREDATA subdirectory of the directory in which it found the FILE.DDF file. The specifications for the FILE.DDF file are:
*If bit 4 equals 1, the file is a dictionary (.DDF) file. If bit 4 equals 0, the file is a user-defined file. The "Xf$" prefixes are part of the Novell definition for these files. Position is the offset from the beginning of the column, and Length is the length of the field. FIELD.DDF: The FIELD.DDF file contains:
This file contains actual field definitions. The first 17 rows contain the description of each field in FILE.DDF, FIELD.DDF (self-describing), and INDEX.DDF. The definitions are related to the FILE.DDF file by the Xe$File field, which correlates to the Xf$ID field in FILE.DDF. Thus, the first 4 records are for file number 1, which in FILE.DDF is FILE.DDF, the next 8 records are for file number 2, which in FILE.DDF is FIELD.DDF, and 5 records are for file number 3, INDEX.DDF. Note that the records do not have to be in this order, or have to contain these file numbers, although they usually do. Some .DDF builders will put them in order, others do not. However, the records in FIELD.DDF must be in the same order as the fields within the file they describe. For example, the first record in FIELD.DDF for file number 1 must describe the first field in file number 1, and so on. In this example, file number 4, TEST.DAT in FILE.DDF, has 4 fields:
If any of the fields were of the Btrieve Numeric type, the Xe$Dec field would contain the number of decimal points. The specifications for FIELD.DDF are:
The "Xe$" prefix is part of the Novell definition for these files. Btrieve is manufactured by Pervasive Software and Xtrieve is manufactured by Novell Inc., vendors independent of Microsoft; we make no warranty, implied or otherwise, regarding these products' performance or reliability. Additional query words: importing exporting linking attaching
Keywords : kb3rdparty IsmBtrv |
Last Reviewed: April 3, 1999 © 2000 Microsoft Corporation. All rights reserved. Terms of Use. |