Provided by: libdbd-xbase-perl_1.08-1_all bug


       XBase::FAQ - Frequently asked questions about the modules


       This is a list of questions people asked since the module has been announced in fall 1997,
       and my answers to them.


       Jan Pazdziora

Questions and answers

       What Perl version do I need? What other modules?
         You need perl 5.10 or newer. You need DBI module version 1.00 or higher, if you want to
         use the DBD driver (which you should).

       Can I use under Windows 95/NT?
         Yes. It's a standard Perl module so there is no reason it shouldn't.  Or, actually,
         there are a lot of reasons why standard thing do not work on systems that are broken,
         but I'm trying hard to workaround these bugs. If you find a problem on these platform,
         send me a description and I'll try to find yet another workaround.

       Is there a choice of the format of the date?
         The only possible format in which you can get the date and that the module expect for
         inserts and updates is a 8 char string 'YYYYMMDD'.  It is not possible to change this
         format. I prefer to do the formatting myself since you have more control over it.

       The "get_record" also returns deleted records. Why?
         Because. You get the _DELETED flag as the first value of the array.  This gives you a
         possibility to decide what to do -- undelete, ignore... It's a feature -- you say you
         want a record of given number, you get it and get additional information, if the record
         is or isn't marked deleted.

       But with DBD::XBase, I do not see the deleted records.
         That's correct: DBD::XBase only gives you records that are positively in the file and
         not deleted. Which shows that is a lower level tool because you can touch
         records that are marked deleted, while DBD::XBase is higher level -- it gives you SQL
         interface and lets you work with the file more naturaly (what is deleted should stay
         deleted). cannot read files created with [your favorite tool].
         Describe exactly, what you expect and what you get. Send me the file (I understand
         attachments, uuencode, tar, gzip and zip) so that I can check what it going on and make understand your file.  A small sample (three rows, or so) are generally enough
         but you can send the whole file if it doesn't have megabytes. Please understand

       How to install the module when I do not have make?
         On Win* platform and with ActiveState port, use ppm to install DBD::XBase from
         ActiveState's site. You can also just copy the files from the lib directory of the
         distribution to where perl can find them. Also check whether your make doesn't hide
         under different names (nmake, gmake). See "README".

       I have make but I cannot install into default directory.
         Ask your sysadmin to do it for your. If he refuses, fire the sysadmin. See "README" for
         how to install into and use nonstandard place for the module.

       Can I access one dbf file both from Perl and (say) Clipper?
         For reading -- yes. For writing -- has a locksh and lockex method to lock the
         file. The question is to what extend Clipper (or Fox* or whatever) uses the same system
         calls, documentation of native XBase applications doesn't tell this. So the answer is
         that for multiple updates you should probably consider real RDBMS system (PostgreSQL,
         MySQL, Oracle, to name a few). breaks my accented characters.
         No, it doesn't. The character data is returned exactly as it appears in the dbf/dbt
         file. You probably brought the file from different system that uses differend character
         encodings. So some bytes in the strings have different meaning on that system. You also
         probably have fonts in different encoding on that system. In the Czech language, we have
         about 6 different encoding that affect possition at which accented characters appear.

         So what you really want to do is to use some external utility to convert the strings to
         encoding you need -- for example, when I bring the dbf from Win*, it often is in the
         Windows-1250 or PC-Latin-2 encoding, while the standard is ISO-8859-2. I use my utility
         Cz::Cstocs to do the conversion, you maight also try GNU program recode or use
         Text::Iconv Perl module.

       How do I access the fields in the memo file?
         Just read the memo field, it will fetch the data from the memo file for you

       Matching with "field = '%str%'" doesn't work.
         If you want to match wildcards with DBD::XBase, you have to use "like":

                 select * from table where field like '%str%'

       Can I sue you if corrupts my data?
         No. At least, I hope no. The software is provided without any warranty, in a hope you
         might find is useful. Which is by the way the same as with most other software, even if
         you pay for that. What is different with is the fact that if you
         find out that the results are different from those expected, you are welcome to contact
         me, describe the problem and send me the files that give troubles to the module, and
         I'll try to find fix the module.

       What dbf/other files standard does the module support?
         I try to support any file that looks reasonably as dbf/dbt/fpt/smt/ndx/ntx/mdx/idx/cdx.
         There are many clones of XBase-like software, each adding its own extension. The module
         tries to accept all different variations. To do that, I need your cooperation however --
         usually good description of the problem, file sample and expected results lead to rather
         fast patch.

       What SQL standard does the DBD::XBase support?
         If supports a reasonable subset of the SQL syntax, IMHO. So you can do select, delete,
         insert and update, create and drop table. If there is something that should be added,
         let me know and I will consider it.  Having said that, I do not expect to ever support
         joins, for example.  This module is more a parser to read files from your legacy
         applications that a RDBMS -- you can find plenty of them around -- use them.

       I downloaded you module I do not know how to install it.
         Did you follow the steps in the "README" and "INSTALL" files? Where did it fail? This
         module uses a standard way modules in Perl are installed. If you've never installed a
         module on your system and your system is so non-standard that the general instruction do
         not help, you should contact your system administrator or the support for your system.

       "select max(field) from table" does not work.
         Aggregate functions are not supported. It would probably be very slow, since the DBD
         doesn't make use of indexes at the moment. I do not have plans to add this support in
         some near future.

       "DBI->connect" says that the directory doesn't exist ...
         ... but it's there. Is DBD::XBase mad or what?

         The third part of the first parameter to the connect is the directory where DBD::XBase
         will look for the dbf files. During connect, the module checks "if -d $directory". So if
         it says it's not there, it's not there and the only thing DBD::XBase can do about it is
         to report it to you. It might be that the directory is not mounted, you do not have
         permissions to it, the script is running under different UID than when you try it from
         command line, or you use relative patch and run the script from a different directory
         (pwd) than you expect. Anyway, add

                 die "Error reading $dir: $!\n" unless -d $dir;

         to your script and you will see that it's not DBD::XBase problem.

       The stops after reading n records ...
         ... why doesn't it read all 10 x n records?

         Check if the file isn't truncated. "dbf_dump -i file.dbf" will tell you the expected
         number of records and length of one record, like

                 Filename:       file.dbf
                 Version:        0x03 (ver. 3)
                 Num of records: 65
                 Header length:  1313
                 Record length:  1117
                 Last change:    1998/12/18
                 Num fields:     40

         So the expected length of the file is at least 1313 + 65 * 1117. If it's shorter, you've
         got damaged file and only reads as much rows as it can find in the

       How is this DBD::XBase related to DBD::ODBC?
         DBD::XBase reads the dbf files directly, using the (included) module. So it
         will run on any platform with reasonable new perl. With DBD::ODBC, you need an ODBC
         server, or some program, that DBD::ODBC could talk to. Many proprietary software can
         serve as ODBC source for dbf files, it just doesn't seem to run on Un*x systems. And is
         also much more resource intensive, if you just need to read the file record by record
         and convert it to HTML page or do similarly simple operation with it.

       How do I pack the dbf file, after the records were deleted? doesn't support this directly. You'd probably want to create new table, copy
         the data and rename back. Patches are always welcome.

       Foxpro doesn't see all fields in dbf created with
         Put 'version' => 3 options in to the create call -- that way we say that the dbf file is
         dBaseIII style.