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NAME

       XBase - Perl module for reading and writing the dbf files

SYNOPSIS

         use XBase;
         my $table = new XBase "dbase.dbf" or die XBase->errstr;
         for (0 .. $table->last_record) {
               my ($deleted, $id, $msg)
                       = $table->get_record($_, "ID", "MSG");
               print "$id:	$msg
" unless $deleted;
         }

DESCRIPTION

       This module can read and write XBase database files, known as dbf in
       dBase and FoxPro world. It also reads memo fields from the dbt and fpt
       files, if needed. An alpha code of reading index support for ndx, ntx,
       mdx, idx and cdx is available for testing -- see the DBD::Index(3) man
       page. Module XBase provides simple native interface to XBase files.
       For DBI compliant database access, see the DBD::XBase and DBI modules
       and their man pages.

       The following methods are supported by XBase module:

   General methods
       new Creates the XBase object, loads the info about the table form the
           dbf file. The first parameter should be the name of existing dbf
           file (table, in fact) to read. A suffix .dbf will be appended if
           needed.  This method creates and initializes new object, will also
           check for memo file, if needed.

           The parameters can also be specified in the form of hash: value of
           name is then the name of the table, other flags supported are:

           memofile specifies non standard name for the associated memo file.
           By default it's the name of the dbf file, with extension dbt or
           fpt.

           ignorememo ignore memo file at all. This is useful if you've lost
           the dbt file and you do not need it. Default is false.

           memosep separator of memo records in the dBase III dbt files. The
           standard says it should be "". There are however
           implamentations that only put in one "". XBase.pm tries to
           guess which is valid for your dbt but if it fails, you can tell it
           yourself.

           nolongchars prevents XBase to treat the decimal value of character
           fields as high byte of the length -- there are some broken products
           around producing character fields with decimal values set.

               my $table = new XBase "table.dbf" or die XBase->errstr;

               my $table = new XBase "name" => "table.dbf",
                                                   "ignorememo" => 1;

           recompute_lastrecno forces XBase.pm to disbelieve the information
           about the number of records in the header of the dbf file and
           recompute the number of records. Use this only if you know that
           some other software of yours produces incorrect headers.

       close
           Closes the object/file, no arguments.

       create
           Creates new database file on disk and initializes it with 0
           records.  A dbt (memo) file will be also created if the table
           contains some memo fields. Parameters to create are passed as hash.

           You can call this method as method of another XBase object and then
           you only need to pass name value of the hash; the structure
           (fields) of the new file will be the same as of the original
           object.

           If you call create using class name (XBase), you have to (besides
           name) also specify another four values, each being a reference to
           list: field_names, field_types, field_lengths and field_decimals.
           The field types are specified by one letter strings (C, N, L, D,
           ...). If you set some value as undefined, create will make it into
           some reasonable default.

               my $newtable = $table->create("name" => "copy.dbf");

               my $newtable = XBase->create("name" => "copy.dbf",
                           "field_names" => [ "ID", "MSG" ],
                           "field_types" => [ "N", "C" ],
                           "field_lengths" => [ 6, 40 ],
                           "field_decimals" => [ 0, undef ]);

           Other attributes are memofile for non standard memo file location,
           codepage to set the codepage flag in the dbf header (it does not
           affect how XBase.pm reads or writes the data though, just to make
           FoxPro happy), and version to force different version of the dbt
           (dbt) file. The default is the version of the object from which you
           create the new one, or 3 if you call this as class method
           (XBase->create).

           The new file mustn't exist yet -- XBase will not allow you to
           overwrite existing table. Use drop (or unlink) to delete it first.

       drop
           This method closes the table and deletes it on disk (including
           associated memo file, if there is any).

       last_record
           Returns number of the last record in the file. The lines deleted
           but present in the file are included in this number.

       last_field
           Returns number of the last field in the file, number of fields
           minus 1.

       field_names, field_types, field_lengths, field_decimals
           Return list of field names and so on for the dbf file.

       field_type, field_length, field_decimal
           For a field name, returns the appropriate value. Returns undef if
           the field doesn't exist in the table.

   Reading the data one by one
       When dealing with the records one by one, reading or writing (the
       following six methods), you have to specify the number of the record in
       the file as the first argument. The range is "0 ..
       $table->last_record".

       get_record
           Returns a list of data (field values) from the specified record
           (line of the table). The first parameter in the call is the number
           of the record. If you do not specify any other parameters, all
           fields are returned in the same order as they appear in the file.
           You can also put list of field names after the record number and
           then only those will be returned. The first value of the returned
           list is always the 1/0 "_DELETED" value saying whether the record
           is deleted or not, so on success, get_record never returns empty
           list.

       get_record_nf
           Instead if the names of the fields, you can pass list of numbers of
           the fields to read.

       get_record_as_hash
           Returns hash (in list context) or reference to hash (in scalar
           context) containing field values indexed by field names. The name
           of the deleted flag is "_DELETED". The only parameter in the call
           is the record number. The field names are returned as uppercase.

   Writing the data
       All three writing methods always undelete the record. On success they
       return true -- the record number actually written.

       set_record
           As parameters, takes the number of the record and the list of
           values of the fields. It writes the record to the file. Unspecified
           fields (if you pass less than you should) are set to undef/empty.

       set_record_hash
           Takes number of the record and hash as parameters, sets the fields,
           unspecified are undefed/emptied.

       update_record_hash
           Like set_record_hash but fields that do not have value specified in
           the hash retain their value.

       To explicitly delete/undelete a record, use methods delete_record or
       undelete_record with record number as a parameter.

       Assorted examples of reading and writing:

           my @data = $table->get_record(3, "jezek", "krtek");
           my $hashref = $table->get_record_as_hash(38);
           $table->set_record_hash(8, "jezek" => "jezecek",
                                               "krtek" => 5);
           $table->undelete_record(4);

       This is a code to update field MSG in record where ID is 123.

           use XBase;
           my $table = new XBase "test.dbf" or die XBase->errstr;
           for (0 .. $table->last_record) {
               my ($deleted, $id) = $table->get_record($_, "ID")
               die $table->errstr unless defined $deleted;
               next if $deleted;
               $table->update_record_hash($_, "MSG" => "New message")
                                                       if $id == 123;
           }

   Sequentially reading the file
       If you plan to sequentially walk through the file, you can create a
       cursor first and then repeatedly call fetch to get next record.

       prepare_select
           As parameters, pass list of field names to return, if no
           parameters, the following fetch will return all fields.

       prepare_select_with_index
           The first parameter is the file name of the index file, the rest is
           as above. For index types that can hold more index structures in on
           file, use arrayref instead of the file name and in that array
           include file name and the tag name, and optionaly the index type.
           The fetch will then return records in the ascending order,
           according to the index.

       Prepare will return object cursor, the following method are methods of
       the cursor, not of the table.

       fetch
           Returns the fields of the next available undeleted record. The list
           thus doesn't contain the "_DELETED" flag since you are guaranteed
           that the record is not deleted.

       fetch_hashref
           Returns a hash reference of fields for the next non deleted record.

       last_fetched
           Returns the number of the record last fetched.

       find_eq
           This only works with cursor created via prepare_select_with_index.
           Will roll to the first record what is equal to specified argument,
           or to the first greater if there is none equal. The following
           fetches then continue normally.

       Examples of using cursors:

           my $table = new XBase "names.dbf" or die XBase->errstr;
           my $cursor = $table->prepare_select("ID", "NAME", "STREET");
           while (my @data = $cursor->fetch) {
               ### do something here, like print "@data
";
           }

           my $table = new XBase "employ.dbf";
           my $cur = $table->prepare_select_with_index("empid.ndx");
           ## my $cur = $table->prepare_select_with_index(
                       ["empid.cdx", "ADDRES", "char"], "id", "address");
           $cur->find_eq(1097);
           while (my $hashref = $cur->fetch_hashref
                               and $hashref->{"ID"} == 1097) {
               ### do something here with $hashref
           }

       The second example shows that after you have done find_eq, the fetches
       continue untill the end of the index, so you have to check whether you
       are still on records with given value. And if there is no record with
       value 1097 in the indexed field, you will just get the next record in
       the order.

       The updating example can be rewritten to:

           use XBase;
           my $table = new XBase "test.dbf" or die XBase->errstr;
           my $cursor = $table->prepare_select("ID")
           while (my ($id) = $cursor->fetch) {
               $table->update_record_hash($cursor->last_fetched,
                               "MSG" => "New message") if $id == 123
           }

   Dumping the content of the file
       A method get_all_records returns reference to an array containing array
       of values for each undeleted record at once. As parameters, pass list
       of fields to return for each record.

       To print the content of the file in a readable form, use method
       dump_records. It prints all not deleted records from the file. By
       default, all fields are printed, separated by colons, one record on a
       row. The method can have parameters in a form of a hash with the
       following keys:

       rs  Record separator, string, newline by default.

       fs  Field separator, string, one colon by default.

       fields
           Reference to a list of names of the fields to print. By default
           it's undef, meaning all fields.

       undef
           What to print for undefined (NULL) values, empty string by default.

       Example of use is

           use XBase;
           my $table = new XBase "table" or die XBase->errstr;
           $table->dump_records("fs" => " | ", "rs" => " <-+
",
                               "fields" => [ "id", "msg" ]);'

       Also note that there is a script dbf_dump(1) that does the printing.

   Errors and debugging
       If the method fails (returns false or null list), the error message can
       be retrieved via errstr method. If the new or create method fails, you
       have no object so you get the error message using class syntax
       "XBase->errstr()".

       The method header_info returns (not prints) string with information
       about the file and about the fields.

       Module XBase::Base(3) defines some basic functions that are inherited
       by both XBase and XBase::Memo(3) module.

DATA TYPES

       The character fields are returned "as is". No charset or other
       translation is done. The numbers are converted to Perl numbers. The
       date fields are returned as 8 character string of the 'YYYYMMDD' form
       and when inserting the date, you again have to provide it in this form.
       No checking for the validity of the date is done. The datetime field is
       returned in the number of (possibly negative) seconds since 1970/1/1,
       possibly with decimal part (since it allows precision up to 1/1000 s).
       To get the fields, use the gmtime (or similar) Perl function.

       If there is a memo field in the dbf file, the module tries to open file
       with the same name but extension dbt, fpt or smt. It uses module
       XBase::Memo(3) for this. It reads and writes this memo field
       transparently (you do not know about it) and returns the data as single
       scalar.

INDEX, LOCKS

       New: A support for ndx, ntx, mdx, idx and cdx index formats is
       available with alpha status for testing. Some of the formats are
       already rather stable (ndx). Please read the XBase::Index(3) man page
       and the eg/use_index file in the distribution for examples and ideas.
       Send me examples of your data files and suggestions for interface if
       you need indexes.

       General locking methods are locksh, lockex and unlock for shared lock,
       exclusive lock and unlock. They call flock but you can redefine then in
       XBase::Base package.

INFORMATION SOURCE

       This module is built using information from and article XBase File
       Format Description by Erik Bachmann, URL

               http://www.clicketyclick.dk/databases/xbase/format/

       Thanks a lot.

VERSION

       1.02

AVAILABLE FROM

       http://www.adelton.com/perl/DBD-XBase/

AUTHOR

       (c) 1997--2011 Jan Pazdziora.

       All rights reserved. This package is free software; you can
       redistribute it and/or modify it under the same terms as Perl itself.

       Contact the author at jpx dash perl at adelton dot com.

THANKS

       Many people have provided information, test files, test results and
       patches. This project would not be so great without them. See the
       Changes file for (I hope) complete list. Thank you all, guys!

       Special thanks go to Erik Bachmann for his great page about the file
       structures; to Frans van Loon, William McKee, Randy Kobes and Dan
       Albertsson for longtime cooperation and many emails we've exchanged
       when fixing and polishing the modules' behaviour; and to Dan Albertsson
       for providing support for the project.

SEE ALSO

       perl(1); XBase::FAQ(3); DBD::XBase(3) and DBI(3) for DBI interface;
       dbf_dump(1)



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