dbi::dbd.3

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.

.\" Automatically generated by Pod::Man 2.16 (Pod::Simple 3.05)
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sh \" Subsection heading
.br
.if t .Sp
.ne 5
.PP
\fB\\$1\fR
.PP
..
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" Set up some character translations and predefined strings.  \*(-- will
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
.\" double quote, and \*(R" will give a right double quote.  \*(C+ will
.\" give a nicer C++.  Capital omega is used to do unbreakable dashes and
.\" therefore won't be available.  \*(C` and \*(C' expand to `' in nroff,
.\" nothing in troff, for use with C<>.
.tr \(*W-
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.ie n \{\
.    ds -- \(*W-
.    ds PI pi
.    if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
.    if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\"  diablo 12 pitch
.    ds L" ""
.    ds R" ""
.    ds C` ""
.    ds C' ""
'br\}
.el\{\
.    ds -- \|\(em\|
.    ds PI \(*p
.    ds L" ``
.    ds R" ''
'br\}
.\"
.\" Escape single quotes in literal strings from groff's Unicode transform.
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\"
.\" If the F register is turned on, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index
.\" entries marked with X<> in POD.  Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.ie \nF \{\
.    de IX
.    tm Index:\\$1\t\\n%\t"\\$2"
..
.    nr % 0
.    rr F
.\}
.el \{\
.    de IX
..
.\}
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear.  Run.  Save yourself.  No user-serviceable parts.
.    \" fudge factors for nroff and troff
.if n \{\
.    ds #H 0
.    ds #V .8m
.    ds #F .3m
.    ds #[ \f1
.    ds #] \fP
.\}
.if t \{\
.    ds #H ((1u-(\\\\n(.fu%2u))*.13m)
.    ds #V .6m
.    ds #F 0
.    ds #[ \&
.    ds #] \&
.\}
.    \" simple accents for nroff and troff
.if n \{\
.    ds ' \&
.    ds ` \&
.    ds ^ \&
.    ds , \&
.    ds ~ ~
.    ds /
.\}
.if t \{\
.    ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
.    ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
.    ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
.    ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
.    ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
.    ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
.\}
.    \" troff and (daisy-wheel) nroff accents
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
.ds ae a\h'-(\w'a'u*4/10)'e
.ds Ae A\h'-(\w'A'u*4/10)'E
.    \" corrections for vroff
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
.    \" for low resolution devices (crt and lpr)
.if \n(.H>23 .if \n(.V>19 \
\{\
.    ds : e
.    ds 8 ss
.    ds o a
.    ds d- d\h'-1'\(ga
.    ds D- D\h'-1'\(hy
.    ds th \o'bp'
.    ds Th \o'LP'
.    ds ae ae
.    ds Ae AE
.\}
.rm #[ #] #H #V #F C
.\" ========================================================================
.\"
.IX Title "DBI::DBD 3"
.TH DBI::DBD 3 "2007-09-26" "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.
.if n .ad l
.nh
.SH "NAME"
DBI::DBD \- Perl DBI Database Driver Writer's Guide
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&  perldoc DBI::DBD
.Ve
.Sh "Version and volatility"
.IX Subsection "Version and volatility"
This document is \fIstill\fR a minimal draft which is in need of further work.
.PP
The changes will occur both because the \fB\s-1DBI\s0\fR specification is changing
and hence the requirements on \fB\s-1DBD\s0\fR drivers change, and because feedback
from people reading this document will suggest improvements to it.
.PP
Please read the \fB\s-1DBI\s0\fR documentation first and fully, including the \fB\s-1DBI\s0\fR \s-1FAQ\s0.
Then reread the \fB\s-1DBI\s0\fR specification again as you're reading this. It'll help.
.PP
This document is a patchwork of contributions from various authors.
More contributions (preferably as patches) are very welcome.
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This document is primarily intended to help people writing new
database drivers for the Perl Database Interface (Perl \s-1DBI\s0).
It may also help others interested in discovering why the internals of
a \fB\s-1DBD\s0\fR driver are written the way they are.
.PP
This is a guide.  Few (if any) of the statements in it are completely
authoritative under all possible circumstances.  This means you will
need to use judgement in applying the guidelines in this document.
If in \fIany\fR doubt at all, please do contact the \fIdbi-dev\fR mailing list
(details given below) where Tim Bunce and other driver authors can help.
.SH "CREATING A NEW DRIVER"
.IX Header "CREATING A NEW DRIVER"
The first rule for creating a new database driver for the Perl \s-1DBI\s0 is
very simple: \fB\s-1DON\s0'T!\fR
.PP
There is usually a driver already available for the database you want
to use, almost regardless of which database you choose. Very often, the
database will provide an \s-1ODBC\s0 driver interface, so you can often use
\&\fB\s-1DBD::ODBC\s0\fR to access the database. This is typically less convenient
on a Unix box than on a Microsoft Windows box, but there are numerous
options for \s-1ODBC\s0 driver managers on Unix too, and very often the \s-1ODBC\s0
driver is provided by the database supplier.
.PP
Before deciding that you need to write a driver, do your homework to
ensure that you are not wasting your energies.
.PP
[As of December 2002, the consensus is that if you need an \s-1ODBC\s0 driver
manager on Unix, then the unixODBC driver (available from
<http://www.unixodbc.org/>) is the way to go.]
.PP
The second rule for creating a new database driver for the Perl \s-1DBI\s0 is
also very simple: \fBDon't \*(-- get someone else to do it for you!\fR
.PP
Nevertheless, there are occasions when it is necessary to write a new
driver, often to use a proprietary language or \s-1API\s0 to access the
database more swiftly, or more comprehensively, than an \s-1ODBC\s0 driver can.
Then you should read this document very carefully, but with a suitably
sceptical eye.
.PP
If there is something in here that does not make any sense, question it.
You might be right that the information is bogus, but don't come to that
conclusion too quickly.
.Sh "URLs and mailing lists"
.IX Subsection "URLs and mailing lists"
The primary web-site for locating \fB\s-1DBI\s0\fR software and information is
.PP
.Vb 1
\&  http://dbi.perl.org/
.Ve
.PP
There are two main and one auxilliary mailing lists for people working
with \fB\s-1DBI\s0\fR.  The primary lists are \fIdbi\[e-mail]\fR for general users
of \fB\s-1DBI\s0\fR and \fB\s-1DBD\s0\fR drivers, and \fIdbi\[e-mail]\fR mainly for \fB\s-1DBD\s0\fR driver
writers (don't join the \fIdbi-dev\fR list unless you have a good reason).
The auxilliary list is \fIdbi\[e-mail]\fR for announcing new
releases of \fB\s-1DBI\s0\fR or \fB\s-1DBD\s0\fR drivers.
.PP
You can join these lists by accessing the web-site <http://dbi.perl.org/>.
The lists are closed so you cannot send email to any of the lists
unless you join the list first.
.PP
You should also consider monitoring the \fIcomp.lang.perl.*\fR newsgroups,
especially \fIcomp.lang.perl.modules\fR.
.Sh "The Cheetah book"
.IX Subsection "The Cheetah book"
The definitive book on Perl \s-1DBI\s0 is the Cheetah book, so called because
of the picture on the cover. Its proper title is '\fIProgramming the
Perl \s-1DBI:\s0 Database programming with Perl\fR' by Alligator Descartes
and Tim Bunce, published by O'Reilly Associates, February 2000, \s-1ISBN\s0
1\-56592\-699\-4. Buy it now if you have not already done so, and read it.
.Sh "Locating drivers"
.IX Subsection "Locating drivers"
Before writing a new driver, it is in your interests to find out
whether there already is a driver for your database.  If there is such
a driver, it would be much easier to make use of it than to write your
own!
.PP
The primary web-site for locating Perl software is
<http://search.cpan.org/>.  You should look under the various
modules listings for the software you are after. For example:
.PP
.Vb 1
\&  http://search.cpan.org/modlist/Database_Interfaces
.Ve
.PP
Follow the \fB\s-1DBD::\s0\fR and \fBDBIx::\fR links at the top to see those subsets.
.PP
See the \fB\s-1DBI\s0\fR docs for information on \fB\s-1DBI\s0\fR web sites and mailing lists.
.Sh "Registering a new driver"
.IX Subsection "Registering a new driver"
Before going through any official registration process, you will need
to establish that there is no driver already in the works. You'll do
that by asking the \fB\s-1DBI\s0\fR mailing lists whether there is such a driver
available, or whether anybody is working on one.
.PP
When you get the go ahead, you will need to establish the name of the
driver and a prefix for the driver. Typically, the name is based on the
name of the database software it uses, and the prefix is a contraction
of that. Hence, \fBDBD::Oracle\fR has the name \fIOracle\fR and the prefix
\&'\fIora_\fR'.
.PP
This information will be recorded in the \fB\s-1DBI\s0\fR module. Apart from
documentation purposes, registration is a prerequisite for
installing private methods.
.PP
If you are writing a driver which will not be distributed on \s-1CPAN\s0, then
you should choose a prefix beginning with '\fIx_\fR', to avoid potential
prefix collisions with drivers registered in the future. Thus, if you
wrote a non-CPAN distributed driver called \fBDBD::CustomDB\fR, the prefix
might be '\fIx_cdb_\fR'.
.PP
This document assumes you are writing a driver called \fBDBD::Driver\fR, and
that the prefix '\fIdrv_\fR' is assigned to the driver.
.Sh "Two styles of database driver"
.IX Subsection "Two styles of database driver"
There are two distinct styles of database driver that can be written to
work with the Perl \s-1DBI\s0.
.PP
Your driver can be written in pure Perl, requiring no C compiler.
When feasible, this is the best solution, but most databases are not
written in such a way that this can be done. Some examples of pure
Perl drivers are \fBDBD::File\fR and \fB\s-1DBD::CSV\s0\fR.
.PP
Alternatively, and most commonly, your driver will need to use some C
code to gain access to the database. This will be classified as a C/XS
driver.
.Sh "What code will you write?"
.IX Subsection "What code will you write?"
There are a number of files that need to be written for either a pure
Perl driver or a C/XS driver. There are no extra files needed only by
a pure Perl driver, but there are several extra files needed only by a
C/XS driver.
.PP
\fIFiles common to pure Perl and C/XS drivers\fR
.IX Subsection "Files common to pure Perl and C/XS drivers"
.PP
Assuming that your driver is called \fBDBD::Driver\fR, these files are:
.IP "\(bu" 4
\&\fIMakefile.PL\fR
.IP "\(bu" 4
\&\fI\s-1README\s0\fR
.IP "\(bu" 4
\&\fI\s-1MANIFEST\s0\fR
.IP "\(bu" 4
\&\fIDriver.pm\fR
.IP "\(bu" 4
\&\fIlib/Bundle/DBD/Driver.pm\fR
.IP "\(bu" 4
\&\fIlib/DBD/Driver/Summary.pm\fR
.IP "\(bu" 4
\&\fIt/*.t\fR
.PP
The first four files are mandatory. \fIMakefile.PL\fR is used to control
how the driver is built and installed. The \fI\s-1README\s0\fR file tells people
who download the file about how to build the module and any prerequisite
software that must be installed. The \fI\s-1MANIFEST\s0\fR file is used by the
standard Perl module distribution mechanism. It lists all the source
files that need to be distributed with your module. \fIDriver.pm\fR is what
is loaded by the \fB\s-1DBI\s0\fR code; it contains the methods peculiar to your
driver.
.PP
The \fIlib/Bundle/DBD/Driver.pm\fR file allows you to specify other Perl
modules on which yours depends in a format that allows someone to type a
simple command and ensure that all the pre-requisites are in place as
well as building your driver.
.PP
The \fIlib/DBD/Driver/Summary.pm\fR file contains (an updated version of) the
information that was included \- or that would have been included \- in
the appendices of the Cheetah book as a summary of the abilities of your