1XBase::FAQ(3)         User Contributed Perl Documentation        XBase::FAQ(3)
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NAME

6       XBase::FAQ - Frequently asked questions about the XBase.pm/DBD::XBase
7       modules
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DESCRIPTION

10       This is a list of questions people asked since the module has been
11       announced in fall 1997, and my answers to them.
12

AUTHOR

14       Jan Pazdziora
15

Questions and answers

17       What Perl version do I need? What other modules?
18         You need perl 5.10 or newer. You need DBI module version 1.00 or
19         higher, if you want to use the DBD driver (which you should).
20
21       Can I use XBase.pm under Windows 95/NT?
22         Yes. It's a standard Perl module so there is no reason it shouldn't.
23         Or, actually, there are a lot of reasons why standard thing do not
24         work on systems that are broken, but I'm trying hard to workaround
25         these bugs. If you find a problem on these platform, send me a
26         description and I'll try to find yet another workaround.
27
28       Is there a choice of the format of the date?
29         The only possible format in which you can get the date and that the
30         module expect for inserts and updates is a 8 char string 'YYYYMMDD'.
31         It is not possible to change this format. I prefer to do the
32         formating myself since you have more control over it.
33
34       The "get_record" also returns deleted records. Why?
35         Because. You get the _DELETED flag as the first value of the array.
36         This gives you a possibility to decide what to do -- undelete,
37         ignore... It's a feature -- you say you want a record of given
38         number, you get it and get additional information, if the record is
39         or isn't marked deleted.
40
41       But with DBD::XBase, I do not see the deleted records.
42         That's correct: DBD::XBase only gives you records that are positively
43         in the file and not deleted. Which shows that XBase.pm is a lower
44         level tool because you can touch records that are marked deleted,
45         while DBD::XBase is higher level -- it gives you SQL interface and
46         let's you work with the file more naturaly (what is deleted should
47         stay deleted).
48
49       XBase.pm cannot read files created with [your favorite tool].
50         Describe exactly, what you expect and what you get. Send me the file
51         (I understand attachments, uuencode, tar, gzip and zip) so that I can
52         check what it going on and make XBase.pm undestand your file.  A
53         small sample (three rows, or so) are generally enough but you can
54         send the whole file if it doesn't have megabytes. Please understand
55
56       How to install the module when I do not have make?
57         On Win* platform and with ActiveState port, use ppm to install
58         DBD::XBase from ActiveState's site. You can also just copy the files
59         from the lib directory of the distribution to where perl can find
60         them. Also check whether your make doesn't hide under different names
61         (nmake, gmake). See "README".
62
63       I have make but I cannot install into default directory.
64         Ask your sysadmin to do it for your. If he refuses, fire the
65         sysadmin. See "README" for how to install into and use nonstandard
66         place for the module.
67
68       Can I access one dbf file both from Perl and (say) Clipper?
69         For reading -- yes. For writing -- XBase.pm has a locksh and lockex
70         method to lock the file. The question is to what extend Clipper (or
71         Fox* or whatever) uses the same system calls, documentation of native
72         XBase applications doesn't tell this. So the answer is that for
73         multiple updates you should probably consider real RDBMS system
74         (PostgreSQL, MySQL, Oracle, to name a few).
75
76       XBase.pm/DBD::XBase breaks my accented characters.
77         No, it doesn't. The character data is returned exactly as it appears
78         in the dbf/dbt file. You probably brought the file from different
79         system that uses differend character encodings. So some bytes in the
80         strings have different meaning on that system. You also probably have
81         fonts in different encoding on that system. In the Czech language, we
82         have about 6 different encoding that affect possition at which
83         accented characters appear.
84
85         So what you really want to do is to use some external utility to
86         convert the strings to encoding you need -- for example, when I bring
87         the dbf from Win*, it often is in the Windows-1250 or PC-Latin-2
88         encoding, while the standard is ISO-8859-2. I use my utility
89         Cz::Cstocs to do the conversion, you maight also try GNU program
90         recode or use Text::Iconv Perl module.
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92       How do I access the fields in the memo file?
93         Just read the memo field, it will fetch the data from the memo file
94         for you transparently.
95
96       Matching with "field = '%str%'" doesn't work.
97         If you want to match wildcards with DBD::XBase, you have to use
98         "like":
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100                 select * from table where field like '%str%'
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102       Can I sue you if XBase.pm/DBD::XBase corrupts my data?
103         No. At least, I hope no. The software is provided without any
104         warranty, in a hope you might find is usefull. Which is by the way
105         the same as with most other software, even if you pay for that. What
106         is different with XBase.pm/DBD::XBase is the fact that if you find
107         out that the results are different from those expected, you are
108         welcome to contact me, describe the problem and send me the files
109         that give troubles to the module, and I'll try to find fix the
110         module.
111
112       What dbf/other files standard does the module support?
113         I try to support any file that looks reasonably as
114         dbf/dbt/fpt/smt/ndx/ntx/mdx/idx/cdx. There are many clones of XBase-
115         like software, each adding its own extension. The module tries to
116         accept all different variations. To do that, I need your cooperation
117         however -- usually good description of the problem, file sample and
118         expected results lead to rather fast patch.
119
120       What SQL standard does the DBD::XBase support?
121         If supports a reasonable subset of the SQL syntax, IMHO. So you can
122         do select, delete, insert and update, create and drop table. If there
123         is something that should be added, let me know and I will consider
124         it.  Having said that, I do not expect to ever support joins, for
125         example.  This module is more a parser to read files from your legacy
126         applications that a RDBMS -- you can find plenty of them around --
127         use them.
128
129       I downloaded you module I do not know how to install it.
130         Did you follow the steps in the "README" and "INSTALL" files? Where
131         did it fail? This module uses a standard way modules in Perl are
132         installed. If you've never installed a module on your system and your
133         system is so non-standard that the general instruction do not help,
134         you should contact your system administrator or the support for your
135         system.
136
137       "select max(field) from table" does not work.
138         Aggregate functions are not supported. It would probably be very
139         slow, since the DBD doesn't make use of indexes at the moment. I do
140         not have plans to add this support in some near future.
141
142       "DBI->connect" says that the directory doesn't exist ...
143         ... but it's there. Is DBD::XBase mad or what?
144
145         The third part of the first parameter to the connect is the directory
146         where DBD::XBase will look for the dbf files. During connect, the
147         module checks "if -d $directory". So if it says it's not there, it's
148         not there and the only thing DBD::XBase can do about it is to report
149         it to you. It might be that the directory is not mounted, you do not
150         have permissions to it, the script is running under different UID
151         than when you try it from command line, or you use relative patch and
152         run the script from a different directory (pwd) than you expect.
153         Anyway, add
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155                 die "Error reading $dir: $!\n" unless -d $dir;
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157         to your script and you will see that it's not DBD::XBase problem.
158
159       The XBase.pm/dbfdump.pl stops after reading n records ...
160         ... why doesn't it read all 10 x n records?
161
162         Check if the file isn't truncated. "dbfdump.pl -i file.dbf" will tell
163         you the expected number of records and length of one record, like
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165                 Filename:       file.dbf
166                 Version:        0x03 (ver. 3)
167                 Num of records: 65
168                 Header length:  1313
169                 Record length:  1117
170                 Last change:    1998/12/18
171                 Num fields:     40
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173         So the expected length of the file is at least 1313 + 65 * 1117. If
174         it's shorter, you've got damaged file and XBase.pm/dbfdump.pl only
175         reads as much rows as it can find in the dbf.
176
177       How is this DBD::XBase related to DBD::ODBC?
178         DBD::XBase reads the dbf files directly, using the (included)
179         XBase.pm module. So it will run on any platform with reasonable new
180         perl. With DBD::ODBC, you need an ODBC server, or some program, that
181         DBD::ODBC could talk to. Many proprietary software can serve as ODBC
182         source for dbf files, it just doesn't seem to run on Un*x systems.
183         And is also much more resource intensive, if you just need to read
184         the file record by record and convert it to HTML page or do similary
185         simple operation with it.
186
187       How do I pack the dbf file, after the records were deleted?
188         XBase.pm doesn't support this directly. You'd probably want to create
189         new table, copy the data and rename back. Patches are always welcome.
190
191       Foxpro doesn't see all fields in dbf created with XBase.pm.
192         Put 'version' => 3 options in to the create call -- that way we say
193         that the dbf file is dBaseIII style.
194

AVAILABLE FROM

196       http://www.adelton.com/perl/DBD-XBase/
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200perl v5.32.1                      2021-01-27                     XBase::FAQ(3)
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