dbd::file.3

来自「视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.」· 3 代码 · 共 266 行

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.\" ========================================================================
.\"
.IX Title "DBD::File 3"
.TH DBD::File 3 "2007-09-27" "perl v5.10.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.SH "NAME"
DBD::File \- Base class for writing DBI drivers
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 4
\& This module is a base class for writing other DBDs.
\& It is not intended to function as a DBD itself.
\& If you want to access flatfiles, use DBD::AnyData, or DBD::CSV,
\& (both of which are subclasses of DBD::File).
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The DBD::File module is not a true \s-1DBI\s0 driver, but an abstract
base class for deriving concrete \s-1DBI\s0 drivers from it. The implication is,
that these drivers work with plain files, for example \s-1CSV\s0 files or
\&\s-1INI\s0 files. The module is based on the SQL::Statement module, a simple
\&\s-1SQL\s0 engine.
.PP
See \s-1DBI\s0 for details on \s-1DBI\s0, SQL::Statement for details on
SQL::Statement and \s-1DBD::CSV\s0 or DBD::IniFile for example
drivers.
.Sh "Metadata"
.IX Subsection "Metadata"
The following attributes are handled by \s-1DBI\s0 itself and not by DBD::File,
thus they all work like expected:
.PP
.Vb 9
\&    Active
\&    ActiveKids
\&    CachedKids
\&    CompatMode             (Not used)
\&    InactiveDestroy
\&    Kids
\&    PrintError
\&    RaiseError
\&    Warn                   (Not used)
.Ve
.PP
The following \s-1DBI\s0 attributes are handled by DBD::File:
.IP "AutoCommit" 4
.IX Item "AutoCommit"
Always on
.IP "ChopBlanks" 4
.IX Item "ChopBlanks"
Works
.IP "\s-1NUM_OF_FIELDS\s0" 4
.IX Item "NUM_OF_FIELDS"
Valid after \f(CW\*(C`$sth\-\*(C'\fRexecute>
.IP "\s-1NUM_OF_PARAMS\s0" 4
.IX Item "NUM_OF_PARAMS"
Valid after \f(CW\*(C`$sth\-\*(C'\fRprepare>
.IP "\s-1NAME\s0" 4
.IX Item "NAME"
Valid after \f(CW\*(C`$sth\-\*(C'\fRexecute>; undef for Non-Select statements.
.IP "\s-1NULLABLE\s0" 4
.IX Item "NULLABLE"
Not really working, always returns an array ref of one's, as \s-1DBD::CSV\s0
doesn't verify input data. Valid after \f(CW\*(C`$sth\-\*(C'\fRexecute>; undef for
Non-Select statements.
.PP
These attributes and methods are not supported:
.PP
.Vb 4
\&    bind_param_inout
\&    CursorName
\&    LongReadLen
\&    LongTruncOk
.Ve
.PP
Additional to the \s-1DBI\s0 attributes, you can use the following dbh
attribute:
.IP "f_dir" 4
.IX Item "f_dir"
This attribute is used for setting the directory where \s-1CSV\s0 files are
opened. Usually you set it in the dbh, it defaults to the current
directory (\*(L".\*(R"). However, it is overwritable in the statement handles.
.Sh "Driver private methods"
.IX Subsection "Driver private methods"
.IP "data_sources" 4
.IX Item "data_sources"
The \f(CW\*(C`data_sources\*(C'\fR method returns a list of subdirectories of the current
directory in the form \*(L"DBI:CSV:f_dir=$dirname\*(R".
.Sp
If you want to read the subdirectories of another directory, use
.Sp
.Vb 2
\&    my($drh) = DBI\->install_driver("CSV");
\&    my(@list) = $drh\->data_sources(\*(Aqf_dir\*(Aq => \*(Aq/usr/local/csv_data\*(Aq );
.Ve
.IP "list_tables" 4
.IX Item "list_tables"
This method returns a list of file names inside \f(CW$dbh\fR\->{'f_dir'}.
Example:
.Sp
.Vb 2
\&    my($dbh) = DBI\->connect("DBI:CSV:f_dir=/usr/local/csv_data");
\&    my(@list) = $dbh\->func(\*(Aqlist_tables\*(Aq);
.Ve
.Sp
Note that the list includes all files contained in the directory, even
those that have non-valid table names, from the view of \s-1SQL\s0.
.SH "KNOWN BUGS"
.IX Header "KNOWN BUGS"
.IP "\(bu" 8
The module is using \fIflock()\fR internally. However, this function is not
available on all platforms. Using \fIflock()\fR is disabled on MacOS and
Windows 95: There's no locking at all (perhaps not so important on
MacOS and Windows 95, as there's a single user anyways).
.SH "AUTHOR AND COPYRIGHT"
.IX Header "AUTHOR AND COPYRIGHT"
This module is currently maintained by
.PP
Jeff Zucker < jzucker @ cpan.org >
.PP
The original author is Jochen Wiedmann.
.PP
Copyright (C) 2004 by Jeff Zucker
Copyright (C) 1998 by Jochen Wiedmann
.PP
All rights reserved.
.PP
You may freely distribute and/or modify this module under the terms of either the \s-1GNU\s0 General Public License (\s-1GPL\s0) or the Artistic License, as specified in
the Perl \s-1README\s0 file.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\s-1DBI\s0, Text::CSV_XS, SQL::Statement