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->fetchow_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:

Class Methods

connect

    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.

host

port

The hostname, if not specified or specified as '', will default to an MySQL daemon running on the local machine on the default port for the UNIX socket.

Should the MySQL daemon 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.

mysql_client_found_rows

Enables (TRUE value) or disables (FALSE value) the flag CLIENT_FOUND_ROWS while connecting to the MySQL server. This has a somewhat funny effect: Without mysql_client_found_rows, if you perform a query like

  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.)

mysql_compression

As of MySQL 3.22.3, a new feature is supported: If your DSN contains the option ``mysql_compression=1'', then the communication between client and server will be compressed.

mysql_connect_timeout

If your DSN contains the option ``mysql_connect_timeout=##'', the connect request to the server will timeout if it has not been successful after the given number of seconds.

mysql_read_default_file

mysql_read_default_group

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

    $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

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

    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

A true value turns on the CLIENT_SSL flag when connecting to the MySQL database:

  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:

mysql_ssl_client_key

mysql_ssl_client_cert

mysql_ssl_ca_file

mysql_ssl_ca_path

mysql_ssl_cipher

These are used to specify the respective parameters of a call to mysql_ssl_set, if mysql_ssl is turned on.

mysql_local_infile

As of MySQL 3.23.49, the LOCAL capability for LOAD DATA may be disabled in the MySQL client library by default. If your DSN contains the option ``mysql_local_infile=1'', LOAD DATA LOCAL will be enabled. (However, this option is *ineffective* if the server has also been configured to disallow LOCAL.)

Prepared statement support (server side prepare)

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 } );

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

Test first without server side prepare, then with.

mysql_embedded_options

The option <mysql_embedded_options> can be used to pass 'command-line' options to embedded server.

Example:

$testdsn=``DBI:mysqlEmb:database=test;mysql_embedded_options=--help,--verbose'';

mysql_embedded_groups

The option <mysql_embedded_groups> can be used to specify the groups in the config file(my.cnf) which will be used to get options for embedded server. If not specified [server] and [embedded] groups will be used.

Example:

$testdsn=``DBI:mysqlEmb:database=test;mysql_embedded_groups=embedded_server,common'';

Private MetaData Methods

ListDBs

    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 daemon running on $hostname, port $port. This method is rarely needed for databases running on localhost: You should use the portable method

    @dbs = DBI->data_sources("mysql");

whenever possible. It is a design problem of this method, that there's no way of supplying a host name or port number to data_sources, that's the only reason why we still support ListDBs. :-(

Server Administration

admin

    $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:

createdb

Creates the database $dbname. Equivalent to ``m(y)sqladmin create $dbname''.

dropdb

Drops the database $dbname. Equivalent to ``m(y)sqladmin drop $dbname''.

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.

shutdown

Silently shuts down the database engine. (Without prompting!) Equivalent to ``m(y)sqladmin shutdown''.

reload

Reloads the servers configuration files and/or tables. This can be particularly important if you modify access privileges or create new users.

DATABASE HANDLES

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:

auto_reconnects_ok

The number of times that DBD::mysql successfully reconnected to the mysql server.

auto_reconnects_failed

The number of times that DBD::mysql tried to reconnect to mysql but failed.

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;

mysql_auto_reconnect

This attribute determines whether DBD::mysql will automatically reconnect to mysql if the connection be lost. This feature defaults to off; however, if either the GATEWAY_INTERFACE or MOD_PERL envionment variable is set, DBD::mysql will turn mysql_auto_reconnect on. Setting mysql_auto_reconnect to on is not advised if 'lock tables' is used because if DBD::mysql reconnect to mysql all table locks will be lost. This attribute is ignored when AutoCommit is turned off, and when AutoCommit is turned off, DBD::mysql will not automatically reconnect to the server.

mysql_use_result

This attribute 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.)

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.

perldoc2tree.cgi: /usr/lib/perl5/vendor_perl/5.8.8/i386-linux-thread-multi/DBD/mysql.pm: unterminated list at =head in paragraph 216. ignoring.

STATEMENT HANDLES

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:

ChopBlanks

this attribute determines whether a fetchrow will chop preceding and trailing blanks off the column values. Chopping blanks does not have impact on the max_length attribute.

mysql_insertid

MySQL has the ability to choose unique key values automatically. If this happened, the new ID will be stored in this attribute. An alternative way for accessing this attribute is via $dbh->{'mysql_insertid'}. (Note we are using the $dbh in this case!)

mysql_is_blob

Reference to an array of boolean values; TRUE indicates, that the respective column is a blob. This attribute is valid for MySQL only.

mysql_is_key

Reference to an array of boolean values; TRUE indicates, that the respective column is a key. This is valid for MySQL only.

mysql_is_num

Reference to an array of boolean values; TRUE indicates, that the respective column contains numeric values.

mysql_is_pri_key

Reference to an array of boolean values; TRUE indicates, that the respective column is a primary key.

mysql_is_auto_increment

Reference to an array of boolean values; TRUE indicates that the respective column is an AUTO_INCREMENT column. This is only valid for MySQL.

mysql_length

mysql_max_length

A reference to an array of maximum column sizes. The max_length is the maximum physically present in the result table, length gives the theoretically possible maximum. max_length is valid for MySQL only.

NAME

A reference to an array of column names.

NULLABLE

A reference to an array of boolean values; TRUE indicates that this column may contain NULL's.

NUM_OF_FIELDS

Number of fields returned by a SELECT or LISTFIELDS statement. You may use this for checking whether a statement returned a result: A zero value indicates a non-SELECT statement like INSERT, DELETE or UPDATE.

mysql_table

A reference to an array of table names, useful in a JOIN result.

TYPE

A reference to an array of column types. The engine's native column types are mapped to portable types like DBI::SQL_INTEGER() or DBI::SQL_VARCHAR(), as good as possible. Not all native types have a meaningfull equivalent, for example DBD::mysql::FIELD_TYPE_INTERVAL is mapped to DBI::SQL_VARCHAR(). If you need the native column types, use mysql_type. See below.

mysql_type

A reference to an array of MySQL's native column types, for example DBD::mysql::FIELD_TYPE_SHORT() or DBD::mysql::FIELD_TYPE_STRING(). Use the TYPE attribute, if you want portable types like DBI::SQL_SMALLINT() or DBI::SQL_VARCHAR().

mysql_type_name

Similar to mysql, but type names and not numbers are returned. Whenever possible, the ANSI SQL name is preferred.

TRANSACTION SUPPORT

Beginning with DBD::mysql 2.0416, transactions are supported. The transaction support works as follows:

• By default AutoCommit mode is on, following the DBI specifications.

• If you execute

      $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:

• You should never change the server variable autocommit manually, unless you are ignoring DBI's transaction support.

• Switching AutoCommit mode from on to off or vice versa may fail. You should always check for errors, when changing AutoCommit mode. The suggested way of doing so is using the DBI flag RaiseError. If you don't like RaiseError, you have to use code like 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.

MULTITHREADING

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.

INSTALLATION

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-(version)
  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.

WIN32 INSTALLATION

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:

-

The current Perl versions (5.6, as of this writing) do have a problem with detecting the C libraries. I recommend to apply the following patch:

  *** 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.

-

Extract the DBD::mysql sources into another directory, for example C:\src\siteperl

-

Open a DOS shell and change directory to C:\src\siteperl.

-

The next step is only required if you repeat building the modules: Make sure that you have a clean build tree by running

  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.

-

Run

  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.

-

Continued in the usual way:

  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.

AUTHORS

A good part of the current version of DBD::mysql is written by Jochen Wiedmann, then was maintained by Rudy Lippan (rlippan@remotelinux.com), and Prepared Statement code written by Alexey Stroganov and Patrick Galbraith, and now maintained by Patrick Galbraith (patg@mysql.com), with the help of various people in the community. The first version's author was Alligator Descartes (descarte@symbolstone.org), who has been 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.

COPYRIGHT

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.

MAILING LIST SUPPORT

This module is maintained and supported on a mailing list,

    perl@lists.mysql.com

To subscribe to this list, send a mail to

    perl-subscribe@lists.mysql.com

or

    perl-digest-subscribe@lists.mysql.com

Mailing list archives are available at

    http://www.progressive-comp.com/Lists/?l=msql-mysql-modules

Additionally you might try the dbi-user mailing list for questions about DBI and its modules in general. Subscribe via

    http://www.fugue.com/dbi

Mailing list archives are at

     http://www.rosat.mpe-garching.mpg.de/mailing-lists/PerlDB-Interest/
     http://outside.organic.com/mail-archives/dbi-users/
     http://www.coe.missouri.edu/~faq/lists/dbi.html

ADDITIONAL DBI INFORMATION

Additional information on the DBI project can be found on the World Wide Web at the following URL:

    http://www.symbolstone.org/technology/perl/DBI

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!