| DBD::mysql - MySQL driver for the Perl5 Database Interface |
DBD::mysql - MySQL driver for the Perl5 Database Interface (DBI)
use DBI;
$dsn = "DBI:mysql:database=$database;host=$hostname;port=$port";
$dbh = DBI->connect($dsn, $user, $password);
$drh = DBI->install_driver("mysql");
@databases = DBI->data_sources("mysql");
or
@databases = DBI->data_sources("mysql",
{"host" => $host, "port" => $port, "user" => $user, password => $pass});
$sth = $dbh->prepare("SELECT * FROM foo WHERE bla");
or
$sth = $dbh->prepare("LISTFIELDS $table");
or
$sth = $dbh->prepare("LISTINDEX $table $index");
$sth->execute;
$numRows = $sth->rows;
$numFields = $sth->{'NUM_OF_FIELDS'};
$sth->finish;
$rc = $drh->func('createdb', $database, $host, $user, $password, 'admin');
$rc = $drh->func('dropdb', $database, $host, $user, $password, 'admin');
$rc = $drh->func('shutdown', $host, $user, $password, 'admin');
$rc = $drh->func('reload', $host, $user, $password, 'admin');
$rc = $dbh->func('createdb', $database, 'admin');
$rc = $dbh->func('dropdb', $database, 'admin');
$rc = $dbh->func('shutdown', 'admin');
$rc = $dbh->func('reload', 'admin');
#!/usr/bin/perl
use strict; use DBI();
# Connect to the database.
my $dbh = DBI->connect("DBI:mysql:database=test;host=localhost",
"joe", "joe's password",
{'RaiseError' => 1});
# Drop table 'foo'. This may fail, if 'foo' doesn't exist.
# Thus we put an eval around it.
eval { $dbh->do("DROP TABLE foo") };
print "Dropping foo failed: $@\n" if $@;
# Create a new table 'foo'. This must not fail, thus we don't
# catch errors.
$dbh->do("CREATE TABLE foo (id INTEGER, name VARCHAR(20))");
# INSERT some data into 'foo'. We are using $dbh->quote() for
# quoting the name.
$dbh->do("INSERT INTO foo VALUES (1, " . $dbh->quote("Tim") . ")");
# Same thing, but using placeholders
$dbh->do("INSERT INTO foo VALUES (?, ?)", undef, 2, "Jochen");
# Now retrieve data from the table.
my $sth = $dbh->prepare("SELECT * FROM foo");
$sth->execute();
while (my $ref = $sth->fetchrow_hashref()) {
print "Found a row: id = $ref->{'id'}, name = $ref->{'name'}\n";
}
$sth->finish();
# Disconnect from the database. $dbh->disconnect();
DBD::mysql is the Perl5 Database Interface driver for the MySQL database. In other words: DBD::mysql is an interface between the Perl programming language and the MySQL programming API that comes with the MySQL relational database management system. Most functions provided by this programming API are supported. Some rarely used functions are missing, mainly because noone ever requested them. :-)
In what follows we first discuss the use of DBD::mysql, because this is what you will need the most. For installation, see the sections on INSTALLATION, and WIN32 INSTALLATION below. See EXAMPLE for a simple example above.
From perl you activate the interface with the statement
use DBI;
After that you can connect to multiple MySQL database servers and send multiple queries to any of them via a simple object oriented interface. Two types of objects are available: database handles and statement handles. Perl returns a database handle to the connect method like so:
$dbh = DBI->connect("DBI:mysql:database=$db;host=$host",
$user, $password, {RaiseError => 1});
Once you have connected to a database, you can can execute SQL statements with:
my $query = sprintf("INSERT INTO foo VALUES (%d, %s)",
$number, $dbh->quote("name"));
$dbh->do($query);
See DBI(3) for details on the quote and do methods. An alternative approach is
$dbh->do("INSERT INTO foo VALUES (?, ?)", undef,
$number, $name);
in which case the quote method is executed automatically. See also the bind_param method in DBI(3). See DATABASE HANDLES below for more details on database handles.
If you want to retrieve results, you need to create a so-called statement handle with:
$sth = $dbh->prepare("SELECT * FROM $table");
$sth->execute();
This statement handle can be used for multiple things. First of all you can retreive a row of data:
my $row = $sth->fetchrow_hashref();
If your table has columns ID and NAME, then $row will be hash ref with keys ID and NAME. See STATEMENT HANDLES below for more details on statement handles.
But now for a more formal approach:
use DBI;
$dsn = "DBI:mysql:$database";
$dsn = "DBI:mysql:database=$database;host=$hostname";
$dsn = "DBI:mysql:database=$database;host=$hostname;port=$port";
$dbh = DBI->connect($dsn, $user, $password);
A database must always be specified.
Should the MySQL server be running on a non-standard port number,
you may explicitly state the port number to connect to in the hostname
argument, by concatenating the hostname and port number together
separated by a colon ( : ) character or by using the port argument.
To connect to a MySQL server on localhost using TCP/IP, you must specify the hostname as 127.0.0.1 (with the optional port).
UPDATE $table SET id = 1 WHERE id = 1
then the MySQL engine will always return 0, because no rows have changed. With mysql_client_found_rows however, it will return the number of rows that have an id 1, as some people are expecting. (At least for compatibility to other engines.)
$dsn = "DBI:mysql:test;mysql_read_default_file=/home/joe/my.cnf";
$dbh = DBI->connect($dsn, $user, $password)
The option mysql_read_default_group can be used to specify the default group in the config file: Usually this is the client group, but see the following example:
[client]
host=localhost
[perl]
host=perlhost
(Note the order of the entries! The example won't work, if you reverse the [client] and [perl] sections!)
If you read this config file, then you'll be typically connected to localhost. However, by using
$dsn = "DBI:mysql:test;mysql_read_default_group=perl;"
. "mysql_read_default_file=/home/joe/my.cnf";
$dbh = DBI->connect($dsn, $user, $password);
you'll be connected to perlhost. Note that if you specify a
default group and do not specify a file, then the default config
files will all be read. See the documentation of
the C function mysql_options() for details.
mysql_socket=/dev/mysql
Usually there's no need for this option, unless you are using another location for the socket than that built into the client.
mysql_ssl=1
This means that your communication with the server will be encrypted.
If you turn mysql_ssl on, you might also wish to use the following flags:
To use server side prepared statements, all you need to do is set the variable mysql_server_prepare in the connect:
$dbh = DBI->connect( ``DBI:mysql:database=test;host=localhost;mysql_server_prepare=1'', ``'', ``'', { RaiseError => 1, AutoCommit => 1 } );
* Note: delimiter for this param is ';'
There are many benefits to using server side prepare statements, mostly if you are performing many inserts because of that fact that a single statement is prepared to accept multiple insert values.
To make sure that the 'make test' step tests whether server prepare works, you just need to export the env variable MYSQL_SERVER_PREPARE:
export MYSQL_SERVER_PREPARE=1
Example:
$testdsn=``DBI:mysqlEmb:database=test;mysql_embedded_options=--help,--verbose'';
Example:
$testdsn=``DBI:mysqlEmb:database=test;mysql_embedded_groups=embedded_server,common'';
my $drh = DBI->install_driver("mysql");
@dbs = $drh->func("$hostname:$port", '_ListDBs');
@dbs = $drh->func($hostname, $port, '_ListDBs');
@dbs = $dbh->func('_ListDBs');
Returns a list of all databases managed by the MySQL server
running on $hostname, port $port. This is a legacy
method. Instead, you should use the portable method
@dbs = DBI->data_sources("mysql");
$rc = $drh->func("createdb", $dbname, [host, user, password,], 'admin');
$rc = $drh->func("dropdb", $dbname, [host, user, password,], 'admin');
$rc = $drh->func("shutdown", [host, user, password,], 'admin');
$rc = $drh->func("reload", [host, user, password,], 'admin');
or
$rc = $dbh->func("createdb", $dbname, 'admin');
$rc = $dbh->func("dropdb", $dbname, 'admin');
$rc = $dbh->func("shutdown", 'admin');
$rc = $dbh->func("reload", 'admin');
For server administration you need a server connection. For obtaining this connection you have two options: Either use a driver handle (drh) and supply the appropriate arguments (host, defaults localhost, user, defaults to '' and password, defaults to ''). A driver handle can be obtained with
$drh = DBI->install_driver('mysql');
Otherwise reuse the existing connection of a database handle (dbh).
There's only one function available for administrative purposes, comparable to the m(y)sqladmin programs. The command being execute depends on the first argument:
It should be noted that database deletion is not prompted for in any way. Nor is it undo-able from DBI.
Once you issue the dropDB() method, the database will be gone!
These method should be used at your own risk.
The DBD::mysql driver supports the following attributes of database handles (read only):
$errno = $dbh->{'mysql_errno'};
$error = $dbh->{'mysql_error'};
$info = $dbh->{'mysql_hostinfo'};
$info = $dbh->{'mysql_info'};
$insertid = $dbh->{'mysql_insertid'};
$info = $dbh->{'mysql_protoinfo'};
$info = $dbh->{'mysql_serverinfo'};
$info = $dbh->{'mysql_stat'};
$threadId = $dbh->{'mysql_thread_id'};
These correspond to mysql_errno(), mysql_error(), mysql_get_host_info(),
mysql_info(), mysql_insert_id(), mysql_get_proto_info(),
mysql_get_server_info(), mysql_stat() and mysql_thread_id(),
respectively.
$info_hashref = $dhb->{mysql_dbd_stats}
DBD::mysql keeps track of some statistics in the mysql_dbd_stats attribute. The following stats are being maintained:
The DBD::mysql driver also supports the following attribute(s) of database
handles (read/write):
$bool_value = $dbh->{mysql_auto_reconnect};
$dbh->{mysql_auto_reconnect} = $AutoReconnect ? 1 : 0;
It is possible to set default value of the mysql_use_result attribute
for $dbh using several ways:
- through DSN
$dbh= DBI->connect("DBI:mysql:test;mysql_use_result=1", "root", "");
- after creation of database handle
$dbh->{'mysql_use_result'}=0; #disable
$dbh->{'mysql_use_result'}=1; #enable
It is possible to set/unset the mysql_use_result attribute after
creation of statement handle. See below.
When set, a data retrieved from a textual column type (char, varchar, etc) will have the UTF-8 flag turned on if necessary. This enables character semantics on that string. You will also need to ensure that your database / table / column is configured to use UTF8. See Chapter 10 of the mysql manual for details.
Additionally, turning on this flag tells MySQL that incoming data should
be treated as UTF-8. This will only take effect if used as part of the
call to connect(). If you turn the flag on after connecting, you will
need to issue the command SET NAMES utf8 to get the same effect.
This option is experimental and may change in future versions.
The statement handles of DBD::mysql support a number of attributes. You access these by using, for example,
my $numFields = $sth->{'NUM_OF_FIELDS'};
Note, that most attributes are valid only after a successfull execute.
An undef value will returned in that case. The most important exception
is the mysql_use_result attribute: This forces the driver to use
mysql_use_result rather than mysql_store_result. The former is faster
and less memory consuming, but tends to block other processes. (That's why
mysql_store_result is the default.)
To set the mysql_use_result attribute, use either of the following:
my $sth = $dbh->prepare("QUERY", { "mysql_use_result" => 1});
or
my $sth = $dbh->prepare("QUERY");
$sth->{"mysql_use_result"} = 1;
Column dependent attributes, for example NAME, the column names, are returned as a reference to an array. The array indices are corresponding to the indices of the arrays returned by fetchrow and similar methods. For example the following code will print a header of table names together with all rows:
my $sth = $dbh->prepare("SELECT * FROM $table");
if (!$sth) {
die "Error:" . $dbh->errstr . "\n";
}
if (!$sth->execute) {
die "Error:" . $sth->errstr . "\n";
}
my $names = $sth->{'NAME'};
my $numFields = $sth->{'NUM_OF_FIELDS'};
for (my $i = 0; $i < $numFields; $i++) {
printf("%s%s", $i ? "," : "", $$names[$i]);
}
print "\n";
while (my $ref = $sth->fetchrow_arrayref) {
for (my $i = 0; $i < $numFields; $i++) {
printf("%s%s", $i ? "," : "", $$ref[$i]);
}
print "\n";
}
For portable applications you should restrict yourself to attributes with capitalized or mixed case names. Lower case attribute names are private to DBD::mysql. The attribute list includes:
Beginning with DBD::mysql 2.0416, transactions are supported. The transaction support works as follows:
$dbh->{'AutoCommit'} = 0;
or
$dbh->{'AutoCommit'} = 1;
then the driver will set the MySQL server variable autocommit to 0 or 1, respectively. Switching from 0 to 1 will also issue a COMMIT, following the DBI specifications.
The methods
$dbh->rollback();
$dbh->commit();
will issue the commands COMMIT and ROLLBACK, respectively. A ROLLBACK will also be issued if AutoCommit mode is off and the database handles DESTROY method is called. Again, this is following the DBI specifications.
Given the above, you should note the following:
$dbh->{'AutoCommit'} = 0;
if ($dbh->{'AutoCommit'}) {
# An error occurred!
}
If you detect an error while changing the AutoCommit mode, you
should no longer use the database handle. In other words, you
should disconnect and reconnect again, because the transaction
mode is unpredictable. Alternatively you may verify the transaction
mode by checking the value of the server variable autocommit.
However, such behaviour isn't portable.
DBD::mysql has a ``reconnect'' feature that handles the so-called
MySQL ``morning bug'': If the server has disconnected, most probably
due to a timeout, then by default the driver will reconnect and
attempt to execute the same SQL statement again. However, this
behaviour is disabled when AutoCommit is off: Otherwise the
transaction state would be completely unpredictable after a
reconnect.
The ``reconnect'' feature of DBD::mysql can be toggled by using the
mysql_auto_reconnect attribute. This behaviour should be turned off
in code that uses LOCK TABLE because if the database server time out
and DBD::mysql reconnect, table locks will be lost without any
indication of such loss.
As of version 3.0002_5, DBD::mysql supports multiple result sets (Thanks to Guy Harrison!). This is the first release of this functionality, so there may be issues. Please report bugs if you run into them!
The basic usage of multiple result sets is
do
{
while (@row= $sth->fetchrow_array())
{
do stuff;
}
} while ($sth->more_results)
An example would be:
$dbh->do("drop procedure if exists someproc") or print $DBI::errstr;
$dbh->do("create procedure somproc() deterministic
begin
declare a,b,c,d int;
set a=1;
set b=2;
set c=3;
set d=4;
select a, b, c, d;
select d, c, b, a;
select b, a, c, d;
select c, b, d, a;
end") or print $DBI::errstr;
$sth=$dbh->prepare('call someproc()') ||
die $DBI::err.": ".$DBI::errstr;
$sth->execute || die DBI::err.": ".$DBI::errstr; $rowset=0;
do {
print "\nRowset ".++$i."\n---------------------------------------\n\n";
foreach $colno (0..$sth->{NUM_OF_FIELDS}) {
print $sth->{NAME}->[$colno]."\t";
}
print "\n";
while (@row= $sth->fetchrow_array()) {
foreach $field (0..$#row) {
print $row[$field]."\t";
}
print "\n";
}
} until (!$sth->more_results)
For more examples, please see the eg/ directory. This is where helpful
DBD::mysql code snippits will be added in the future.
So far, the main issue is if your result sets are ``jagged'', meaning, the number of columns of your results vary. Varying numbers of columns could result in your script crashing. This is something that will be fixed soon.
The multithreading capabilities of DBD::mysql depend completely on the underlying C libraries: The modules are working with handle data only, no global variables are accessed or (to the best of my knowledge) thread unsafe functions are called. Thus DBD::mysql is believed to be completely thread safe, if the C libraries are thread safe and you don't share handles among threads.
The obvious question is: Are the C libraries thread safe? In the case of MySQL the answer is ``mostly'' and, in theory, you should be able to get a ``yes'', if the C library is compiled for being thread safe (By default it isn't.) by passing the option -with-thread-safe-client to configure. See the section on How to make a threadsafe client in the manual.
Windows users may skip this section and pass over to WIN32 INSTALLATION below. Others, go on reading.
First of all, you do not need an installed MySQL server for installing DBD::mysql. However, you need at least the client libraries and possibly the header files, if you are compiling DBD::mysql from source. In the case of MySQL you can create a client-only version by using the configure option --without-server. If you are using precompiled binaries, then it may be possible to use just selected RPM's like MySQL-client and MySQL-devel or something similar, depending on the distribution.
First you need to install the DBI module. For using dbimon, a simple DBI shell it is recommended to install Data::ShowTable another Perl module.
I recommend trying automatic installation via the CPAN module. Try
perl -MCPAN -e shell
If you are using the CPAN module for the first time, it will prompt you a lot of questions. If you finally receive the CPAN prompt, enter
install Bundle::DBD::mysql
If this fails (which may be the case for a number of reasons, for example because you are behind a firewall or don't have network access), you need to do a manual installation. First of all you need to fetch the modules from CPAN search
http://search.cpan.org/
The following modules are required
DBI Data::ShowTable DBD::mysql
Then enter the following commands (note - versions are just examples):
gzip -cd DBI-(version).tar.gz | tar xf - cd DBI-(version) perl Makefile.PL make make test make install
cd .. gzip -cd Data-ShowTable-(version).tar.gz | tar xf - cd Data-ShowTable-3.3 perl Makefile.PL make make install
cd .. gzip -cd DBD-mysql-(version)-tar.gz | tar xf - cd DBD-mysql-(version) perl Makefile.PL make make test make install
During ``perl Makefile.PL'' you will be prompted some questions. Other questions are the directories with header files and libraries. For example, of your file mysql.h is in /usr/include/mysql/mysql.h, then enter the header directory /usr, likewise for /usr/lib/mysql/libmysqlclient.a or /usr/lib/libmysqlclient.so.
If you are using ActivePerl, you may use ppm to install DBD-mysql. For Perl 5.6, upgrade to Build 623 or later, then it is sufficient to run
ppm install DBI ppm install DBD::mysql
If you need an HTTP proxy, you might need to set the environment variable http_proxy, for example like this:
set http_proxy=http://myproxy.com:8080/
As of this writing, DBD::mysql is missing in the ActivePerl 5.8.0 repository. However, Randy Kobes has kindly donated an own distribution and the following might succeed:
ppm install http://theoryx5.uwinnipeg.ca/ppms/DBD-mysql.ppd
Otherwise you definitely *need* a C compiler. And it *must* be the same compiler that was being used for compiling Perl itself. If you don't have a C compiler, the file README.win32 from the Perl source distribution tells you where to obtain freely distributable C compilers like egcs or gcc. The Perl sources are available via CPAN search
http://search.cpan.org
I recommend using the win32clients package for installing DBD::mysql under Win32, available for download on www.tcx.se. The following steps have been required for me:
*** c:\Perl\lib\ExtUtils\Liblist.pm.orig Sat Apr 15 20:03:40 2000
--- c:\Perl\lib\ExtUtils\Liblist.pm Sat Apr 15 20:03:45 2000
***************
*** 230,235 ****
--- 230,239 ----
# add "$Config{installarchlib}/CORE" to default search path
push @libpath, "$Config{installarchlib}/CORE";
+ if ($VC and exists($ENV{LIB}) and defined($ENV{LIB})) {
+ push(@libpath, split(/;/, $ENV{LIB}));
+ }
+
foreach (Text::ParseWords::quotewords('\s+', 0, $potential_libs)){
$thislib = $_;
=item -
Extract sources into C:\. This will create a directory C:\mysql with subdirectories include and lib.
IMPORTANT: Make sure this subdirectory is not shared by other TCX files! In particular do *not* store the MySQL server in the same directory. If the server is already installed in C:\mysql, choose a location like C:\tmp, extract the win32clients there. Note that you can remove this directory entirely once you have installed DBD::mysql.
nmake realclean
If you don't have VC++, replace nmake with your flavour of make. If error messages are reported in this step, you may safely ignore them.
perl Makefile.PL
which will prompt you for some settings. The really important ones are:
Which DBMS do you want to use?
enter a 1 here (MySQL only), and
Where is your mysql installed? Please tell me the directory that contains the subdir include.
where you have to enter the win32clients directory, for example C:\mysql or C:\tmp\mysql.
nmake nmake install
If you want to create a PPM package for the ActiveState Perl version, then modify the above steps as follows: Run
perl Makefile.PL NAME=DBD-mysql BINARY_LOCATION=DBD-mysql.tar.gz nmake ppd nmake
Once that is done, use tar and gzip (for example those from the CygWin32 distribution) to create an archive:
mkdir x86 tar cf x86/DBD-mysql.tar blib gzip x86/DBD-mysql.tar
Put the files x86/DBD-mysql.tar.gz and DBD-mysql.ppd onto some WWW server and install them by typing
install http://your.server.name/your/directory/DBD-mysql.ppd
in the PPM program.
The current version of DBD::mysql is almost completely written by Jochen Wiedmann, and is now being maintained by Patrick Galbraith (patg@mysql.com). The first version's author was Alligator Descartes, who was aided and abetted by Gary Shea, Andreas König and Tim Bunce amongst others.
The Mysql module was originally written by Andreas König <koenig@kulturbox.de>. The current version, mainly an emulation layer, is from Jochen Wiedmann.
This module is Large Portions Copyright (c) 2004-2006 MySQL Patrick Galbraith, Alexey Stroganov, Large Portions Copyright (c) 2003-2005 Rudolf Lippan; Large Portions Copyright (c) 1997-2003 Jochen Wiedmann, with code portions Copyright (c)1994-1997 their original authors This module is released under the same license as Perl itself. See the Perl README for details.
This module is maintained and supported on a mailing list,
perl@lists.mysql.com
To subscribe to this list, go to
http://lists.mysql.com/perl?sub=1
Mailing list archives are available at
Additionally you might try the dbi-user mailing list for questions about DBI and its modules in general. Subscribe via
Mailing list archives are at
http://groups.google.com/group/perl.dbi.users?hl=en&lr=
Also, the main DBI site is at
Additional information on the DBI project can be found on the World Wide Web at the following URL:
http://dbi.perl.org
where documentation, pointers to the mailing lists and mailing list archives and pointers to the most current versions of the modules can be used.
Information on the DBI interface itself can be gained by typing:
perldoc DBI
right now!
Please report bugs, including all the information needed such as DBD::mysql version, MySQL version, OS type/version, etc to this link:
| DBD::mysql - MySQL driver for the Perl5 Database Interface |