dbd::mysql.3

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.\" ========================================================================
.\"
.IX Title "DBD::mysql 3"
.TH DBD::mysql 3 "2007-12-11" "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"
DBD::mysql \- MySQL driver for the Perl5 Database Interface (DBI)
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&    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\->{\*(AqNUM_OF_FIELDS\*(Aq};
\&    $sth\->finish;
\&
\&    $rc = $drh\->func(\*(Aqcreatedb\*(Aq, $database, $host, $user, $password, \*(Aqadmin\*(Aq);
\&    $rc = $drh\->func(\*(Aqdropdb\*(Aq, $database, $host, $user, $password, \*(Aqadmin\*(Aq);
\&    $rc = $drh\->func(\*(Aqshutdown\*(Aq, $host, $user, $password, \*(Aqadmin\*(Aq);
\&    $rc = $drh\->func(\*(Aqreload\*(Aq, $host, $user, $password, \*(Aqadmin\*(Aq);
\&
\&    $rc = $dbh\->func(\*(Aqcreatedb\*(Aq, $database, \*(Aqadmin\*(Aq);
\&    $rc = $dbh\->func(\*(Aqdropdb\*(Aq, $database, \*(Aqadmin\*(Aq);
\&    $rc = $dbh\->func(\*(Aqshutdown\*(Aq, \*(Aqadmin\*(Aq);
\&    $rc = $dbh\->func(\*(Aqreload\*(Aq, \*(Aqadmin\*(Aq);
.Ve
.SH "EXAMPLE"
.IX Header "EXAMPLE"
.Vb 1
\&  #!/usr/bin/perl
\&
\&  use strict;
\&  use DBI();
\&
\&  # Connect to the database.
\&  my $dbh = DBI\->connect("DBI:mysql:database=test;host=localhost",
\&                         "joe", "joe\*(Aqs password",
\&                         {\*(AqRaiseError\*(Aq => 1});
\&
\&  # Drop table \*(Aqfoo\*(Aq. This may fail, if \*(Aqfoo\*(Aq doesn\*(Aqt exist.
\&  # Thus we put an eval around it.
\&  eval { $dbh\->do("DROP TABLE foo") };
\&  print "Dropping foo failed: $@\en" if $@;
\&
\&  # Create a new table \*(Aqfoo\*(Aq. This must not fail, thus we don\*(Aqt
\&  # catch errors.
\&  $dbh\->do("CREATE TABLE foo (id INTEGER, name VARCHAR(20))");
\&
\&  # INSERT some data into \*(Aqfoo\*(Aq. 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\->{\*(Aqid\*(Aq}, name = $ref\->{\*(Aqname\*(Aq}\en";
\&  }
\&  $sth\->finish();
\&
\&  # Disconnect from the database.
\&  $dbh\->disconnect();
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fBDBD::mysql\fR 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 \s-1API\s0 that comes with
the MySQL relational database management system. Most functions
provided by this programming \s-1API\s0 are supported. Some rarely used
functions are missing, mainly because noone ever requested
them. :\-)
.PP
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 \s-1INSTALLATION\s0, and \*(L"\s-1WIN32\s0 \s-1INSTALLATION\s0\*(R"
below. See \s-1EXAMPLE\s0 for a simple example above.
.PP
From perl you activate the interface with the statement
.PP
.Vb 1
\&    use DBI;
.Ve
.PP
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:
.PP
.Vb 2
\&  $dbh = DBI\->connect("DBI:mysql:database=$db;host=$host",
\&                      $user, $password, {RaiseError => 1});
.Ve
.PP
Once you have connected to a database, you can can execute \s-1SQL\s0
statements with:
.PP
.Vb 3
\&  my $query = sprintf("INSERT INTO foo VALUES (%d, %s)",
\&                      $number, $dbh\->quote("name"));
\&  $dbh\->do($query);
.Ve
.PP
See \s-1\fIDBI\s0\fR\|(3) for details on the quote and do methods. An alternative
approach is
.PP
.Vb 2
\&  $dbh\->do("INSERT INTO foo VALUES (?, ?)", undef,
\&           $number, $name);
.Ve
.PP
in which case the quote method is executed automatically. See also
the bind_param method in \s-1\fIDBI\s0\fR\|(3). See \*(L"\s-1DATABASE\s0 \s-1HANDLES\s0\*(R" below
for more details on database handles.
.PP
If you want to retrieve results, you need to create a so-called
statement handle with:
.PP
.Vb 2
\&  $sth = $dbh\->prepare("SELECT * FROM $table");
\&  $sth\->execute();
.Ve
.PP
This statement handle can be used for multiple things. First of all
you can retreive a row of data:
.PP
.Vb 1
\&  my $row = $sth\->fetchrow_hashref();
.Ve
.PP
If your table has columns \s-1ID\s0 and \s-1NAME\s0, then \f(CW$row\fR will be hash ref with
keys \s-1ID\s0 and \s-1NAME\s0. See \*(L"\s-1STATEMENT\s0 \s-1HANDLES\s0\*(R" below for more details on
statement handles.
.PP
But now for a more formal approach:
.Sh "Class Methods"
.IX Subsection "Class Methods"
.IP "\fBconnect\fR" 4
.IX Item "connect"
.Vb 1
\&    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);
.Ve
.Sp
A \f(CW\*(C`database\*(C'\fR must always be specified.
.RS 4
.IP "host" 4
.IX Item "host"
.PD 0
.IP "port" 4
.IX Item "port"
.PD
The hostname, if not specified or specified as '' or 'localhost', will
default to a MySQL server running on the local machine using the default for
the \s-1UNIX\s0 socket. To connect to a MySQL server on the local machine via \s-1TCP\s0,
you must specify the loopback \s-1IP\s0 address (127.0.0.1) as the host.
.Sp
Should the MySQL server be running on a non-standard port number,
you may explicitly state the port number to connect to in the \f(CW\*(C`hostname\*(C'\fR
argument, by concatenating the \fIhostname\fR and \fIport number\fR together
separated by a colon ( \f(CW\*(C`:\*(C'\fR ) character or by using the  \f(CW\*(C`port\*(C'\fR argument.
.Sp
To connect to a MySQL server on localhost using \s-1TCP/IP\s0, you must specify the
hostname as 127.0.0.1 (with the optional port).
.IP "mysql_client_found_rows" 4
.IX Item "mysql_client_found_rows"
Enables (\s-1TRUE\s0 value) or disables (\s-1FALSE\s0 value) the flag \s-1CLIENT_FOUND_ROWS\s0
while connecting to the MySQL server. This has a somewhat funny effect:
Without mysql_client_found_rows, if you perform a query like
.Sp
.Vb 1
\&  UPDATE $table SET id = 1 WHERE id = 1
.Ve
.Sp
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.)
.IP "mysql_compression" 4
.IX Item "mysql_compression"
As of MySQL 3.22.3, a new feature is supported: If your \s-1DSN\s0 contains
the option \*(L"mysql_compression=1\*(R", then the communication between client
and server will be compressed.
.IP "mysql_connect_timeout" 4
.IX Item "mysql_connect_timeout"
If your \s-1DSN\s0 contains the option \*(L"mysql_connect_timeout=##\*(R", the connect
request to the server will timeout if it has not been successful after
the given number of seconds.
.IP "mysql_read_default_file" 4
.IX Item "mysql_read_default_file"
.PD 0
.IP "mysql_read_default_group" 4
.IX Item "mysql_read_default_group"
.PD
These options can be used to read a config file like /etc/my.cnf or
~/.my.cnf. By default MySQL's C client library doesn't use any config
files unlike the client programs (mysql, mysqladmin, ...) that do, but
outside of the C client library. Thus you need to explicitly request
reading a config file, as in
.Sp
.Vb 2
\&    $dsn = "DBI:mysql:test;mysql_read_default_file=/home/joe/my.cnf";
\&    $dbh = DBI\->connect($dsn, $user, $password)
.Ve
.Sp
The option mysql_read_default_group can be used to specify the default
group in the config file: Usually this is the \fIclient\fR group, but
see the following example:
.Sp
.Vb 2
\&    [client]
\&    host=localhost
\&
\&    [perl]
\&    host=perlhost
.Ve
.Sp
(Note the order of the entries! The example won't work, if you reverse
the [client] and [perl] sections!)
.Sp
If you read this config file, then you'll be typically connected to
\&\fIlocalhost\fR. However, by using
.Sp
.Vb 3
\&    $dsn = "DBI:mysql:test;mysql_read_default_group=perl;"
\&        . "mysql_read_default_file=/home/joe/my.cnf";
\&    $dbh = DBI\->connect($dsn, $user, $password);
.Ve
.Sp
you'll be connected to \fIperlhost\fR. 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 \fImysql_options()\fR for details.
.IP "mysql_socket" 4
.IX Item "mysql_socket"
As of MySQL 3.21.15, it is possible to choose the Unix socket that is
used for connecting to the server. This is done, for example, with
.Sp
.Vb 1
\&    mysql_socket=/dev/mysql
.Ve
.Sp
Usually there's no need for this option, unless you are using another
location for the socket than that built into the client.
.IP "mysql_ssl" 4
.IX Item "mysql_ssl"
A true value turns on the \s-1CLIENT_SSL\s0 flag when connecting to the MySQL
database:
.Sp
.Vb 1
\&  mysql_ssl=1
.Ve
.Sp
This means that your communication with the server will be encrypted.
.Sp
If you turn mysql_ssl on, you might also wish to use the following
flags:
.IP "mysql_ssl_client_key" 4
.IX Item "mysql_ssl_client_key"
.PD 0