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DBD::mysql - MySQL driver for the Perl5 Database Interface (DBI)

SYNOPSIS

   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});
   $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');

EXAMPLE

 #!/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: [email protected]\n" if [email protected];
 # 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();

DESCRIPTION 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, "WIN32 INSTALLATION", and "KNOWN BUGS" 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->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.)

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 had to reconnect to mysql

failed_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.

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-E<gt>{'AutoCommit'} = 0;

or

   $dbh-E<gt>{'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-E<gt>rollback();
   $dbh-E<gt>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. SQL EXTENSIONS Certain metadata functions of MySQL that are available on the C API level, haven't been implemented here. Instead they are implemented as "SQL extensions" because they return in fact nothing else but the equivalent of a statement handle. These are:

LISTFIELDS $table Returns a statement handle that describes the columns of $table. Ses the docs of mysql_list_fields (C API) for details.

COMPATIBILITY ALERT The statement attribute TYPE has changed its meaning, as of DBD::mysql 2.0119. Formerly it used to be the an array of native engine's column types, but it is now an array of portable SQL column types. The old attribute is still available as mysql_type.

DBD::mysql is a moving target, due to a number of reasons:

- Of course we have to conform the DBI guidelines and developments.

- We have to keep track with the latest MySQL developments.

- And, surprisingly, we have to be as close to ODBC as possible: This is due to the current direction of DBI.

- And, last not least, as any tool it has a little bit life of its own.

This means that a lot of things had to and have to be changed. As I am not interested in maintaining a lot of compatibility kludges, which only increase the drivers code without being really usefull, I did and will remove some features, methods or attributes.

To ensure a smooth upgrade, the following policy will be applied:

Obsolete features The first step is to declare something obsolete. This means, that no code is changed, but the feature appears in the list of obsolete features. See "Obsolete Features" below.

Deprecated features If the feature has been obsolete for quite some time, typically in the next major stable release, warnings will be inserted in the code. You can suppress these warnings by setting

   $DBD::mysql = 1;

In the docs the feature will be moved from the list of obsolete features to the list of deprecated features. See "Deprecated Features" below.

Removing features Finally features will be removed silently in the next major stable release. The feature will be shown in the list of historic features. See "Historic Features" below.

Example: The statement handle attribute

   $sth->{'LENGTH'}

was declared obsolete in DBD::mysql 2.00xy. It was considered deprecated in DBD::mysql 2.02xy and removed in 2.04xy.

Obsolete Features Database handle attributes The following database handle attributes are declared obsolete in DBD::mysql 2.09. They will be deprecated in 2.11 and removed in 2.13.

$dbh->{'errno'} Replaced by $dbh->{'mysql_errno'}

$dbh->{'errmsg'} Replaced by $dbh->{'mysql_error'}

$dbh->{'hostinfo'} Replaced by $dbh->{'mysql_hostinfo'}

$dbh->{'info'} Replaced by $dbh->{'mysql_info'}

$dbh->{'protoinfo'} Replaced by $dbh->{'mysql_protoinfo'}

$dbh->{'serverinfo'} Replaced by $dbh->{'mysql_serverinfo'}

$dbh->{'stats'} Replaced by $dbh->{'mysql_stat'}

$dbh->{'thread_id'} Replaced by $dbh->{'mysql_thread_id'}

Deprecated Features _ListTables Replace with the standard DBI method $dbh->tables(). See also $dbh->table_info(). Portable applications will prefer

   @tables = map { $_ =~ s/.*\.//; $_ } $dbh-E<gt>tables()

because, depending on the engine, the string "user.table" will be returned, user being the table owner. The method will be removed in DBD::mysql version 2.11xy.

Historic Features _CreateDB _DropDB The methods

   $dbh-E<gt>func($db, '_CreateDB');
   $dbh-E<gt>func($db, '_DropDB');

have been used for creating or dropping databases. They have been removed in 1.21_07 in favour of

   $drh-E<gt>func("createdb", $dbname, $host, "admin")
   $drh-E<gt>func("dropdb", $dbname, $host, "admin")

_ListFields The method

   $sth = $dbh-E<gt>func($table, '_ListFields');

has been used to list a tables columns names, types and other attributes. This method has been removed in 1.21_07 in favour of

   $sth = $dbh-E<gt>prepare("LISTFIELDS $table");

_ListSelectedFields The method

   $sth->func('_ListSelectedFields');

use to return a hash ref of attributes like 'IS_NUM', 'IS_KEY' and so on. These attributes are now accessible via

   $sth-E<gt>{'mysql_is_num'};
   $sth-E<gt>{'mysql_is_key'};

and so on. Thus the method has been removed in 1.21_07.

_NumRows The method

   $sth-E<gt>func('_NumRows');

used to be equivalent to

   $sth-E<gt>rows();

and has been removed in 1.21_07.

_InsertID The method

   $dbh-E<gt>func('_InsertID');

used to be equivalent with

   $dbh-E<gt>{'mysql_insertid'};

Statement handle attributes affected_rows Replaced with $sth->{'mysql_affected_rows'} or the result of $sth->execute().

format_default_size Replaced with $sth->{'PRECISION'}.

format_max_size Replaced with $sth->{'mysql_max_length'}.

format_type_name Replaced with $sth->{'TYPE'} (portable) or $sth->{'mysql_type_name'} (MySQL specific).

format_right_justify Replaced with $sth->->{'TYPE'} (portable) or $sth->{'mysql_is_num'} (MySQL specific).

insertid Replaced with $sth->{'mysql_insertid'}.

IS_BLOB Replaced with $sth->{'TYPE'} (portable) or $sth->{'mysql_is_blob'} (MySQL specific).

is_blob Replaced with $sth->{'TYPE'} (portable) or $sth->{'mysql_is_blob'} (MySQL specific).

IS_PRI_KEY Replaced with $sth->{'mysql_is_pri_key'}.

is_pri_key Replaced with $sth->{'mysql_is_pri_key'}.

IS_NOT_NULL Replaced with $sth->{'NULLABLE'} (do not forget to invert the boolean values).

is_not_null Replaced with $sth->{'NULLABLE'} (do not forget to invert the boolean values).

IS_NUM Replaced with $sth->{'TYPE'} (portable) or $sth->{'mysql_is_num'} (MySQL specific).

is_num Replaced with $sth->{'TYPE'} (portable) or $sth->{'mysql_is_num'} (MySQL specific).

IS_KEY Replaced with $sth->{'mysql_is_key'}.

is_key Replaced with $sth->{'mysql_is_key'}.

MAXLENGTH Replaced with $sth->{'mysql_max_length'}.

maxlength Replaced with $sth->{'mysql_max_length'}.

LENGTH Replaced with $sth->{'PRECISION'} (portable) or $sth->{'mysql_length'} (MySQL specific)

length Replaced with $sth->{'PRECISION'} (portable) or $sth->{'mysql_length'} (MySQL specific)

NUMFIELDS Replaced with $sth->{'NUM_OF_FIELDS'}.

numfields Replaced with $sth->{'NUM_OF_FIELDS'}.

NUMROWS Replaced with the result of $sth->execute() or $sth->{'mysql_affected_rows'}.

TABLE Replaced with $sth->{'mysql_table'}.

table Replaced with $sth->{'mysql_table'}.

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 archives from any CPAN mirror, for example

 ftp://ftp.funet.fi/pub/languages/perl/CPAN/modules/by-module

The following archives are required (version numbers may have changed, I choose those which are current as of this writing):

 DBI/DBI-1.15.tar.gz
 Data/Data-ShowTable-3.3.tar.gz
 DBD/DBD-mysql-2.1001.tar.gz

Then enter the following commands:

 gzip -cd DBI-1.15.tar.gz | tar xf -
 cd DBI-1.15
 perl Makefile.PL
 make
 make test
 make install
 cd ..
 gzip -cd Data-ShowTable-3.3.tar.gz | tar xf -
 cd Data-ShowTable-3.3
 perl Makefile.PL
 make
 make install  # Don't try make test, the test suite is broken
 cd ..
 gzip -cd DBD-mysql-2.1001.tar.gz | tar xf -
 cd DBD-mysql-2.1001
 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 on any CPAN mirror in the src directory, for example

   ftp://ftp.funet.fi/pub/languages/perl/CPAN/src/latest.tar.gz

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 = $_;

- 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 The current version of DBD::mysql is almost completely written by Jochen Wiedmann, and is now being maintained by Rudy Lippan ([email protected]). The first version's author was Alligator Descartes ([email protected]), 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 <[email protected]>. The current version, mainly an emulation layer, is from Jochen Wiedmann.

COPYRIGHT This module is Copyright (c) 2003 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,

   [email protected]

To subscribe to this list, send a mail to

   [email protected]

or

   [email protected]

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!