Provided by: libdbd-mysql-perl_4.025-1ubuntu0.1_amd64 
NAME
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, "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');
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: $@\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();
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 no-one 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 execute SQL statements with:
my $query = sprintf("INSERT INTO foo VALUES (%d, %s)",
$number, $dbh->quote("name"));
$dbh->do($query);
See DBI 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. 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 retrieve 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:
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 '' or 'localhost', will default to
a MySQL server running on the local machine using the default for the UNIX socket.
To connect to a MySQL server on the local machine via TCP, you must specify the
loopback IP address (127.0.0.1) as the host.
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).
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_write_timeout
If your DSN contains the option "mysql_write_timeout=##", the write operation to
the server will timeout if it has not been successful after the given number of
seconds.
mysql_read_timeout
If your DSN contains the option "mysql_read_timeout=##", the read operation to the
server will timeout if it has not been successful after the given number of
seconds.
mysql_init_command
If your DSN contains the option "mysql_init_command=##", then this SQL statement
is executed when connecting to the MySQL server. It is automatically re-executed
if reconnection occurs.
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.)
mysql_multi_statements
As of MySQL 4.1, support for multiple statements separated by a semicolon (;) may
be enabled by using this option. Enabling this option may cause problems if
server-side prepared statements are also enabled.
Prepared statement support (server side prepare)
As of 3.0002_1, server side prepare statements were on by default (if your server
was >= 4.1.3). As of 3.0009, they were off by default again due to issues with the
prepared statement API (all other mysql connectors are set this way until C API
issues are resolved). The requirement to use prepared statements still remains
that you have a server >= 4.1.3
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
mysql_embedded_options
The option <mysql_embedded_options> can be used to pass 'command-line' options to
embedded server.
Example:
use DBI;
$testdsn="DBI:mysqlEmb:database=test;mysql_embedded_options=--help,--verbose";
$dbh = DBI->connect($testdsn,"a","b");
This would cause the command line help to the embedded MySQL server library to be
printed.
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 server running on $hostname, port
$port. This is a legacy method. Instead, you should use the portable method
@dbs = DBI->data_sources("mysql");
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 environment 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.
It is also possible to set the default value of the "mysql_auto_reconnect" attribute
for the $dbh by passing it in the "\%attr" hash for "DBI-"connect>.
Note that if you are using a module or framework that performs reconnections for you
(for example DBIx::Connector in fixup mode), this value must be set to 0.
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. mysql_store_result is the default due to that fact storing the result
is expected behavior with most applications.
It is possible to set the default value of the "mysql_use_result" attribute for the
$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 the
statement handle. See below.
mysql_enable_utf8
This attribute determines whether DBD::mysql should assume strings stored in the
database are utf8. This feature defaults to off.
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.
mysql_bind_type_guessing
This attribute causes the driver (emulated prepare statements) to attempt to guess if
a value being bound is a numeric value, and if so, doesn't quote the value. This was
created by Dragonchild and is one way to deal with the performance issue of using
quotes in a statement that is inserting or updating a large numeric value. This was
previously called "unsafe_bind_type_guessing" because it is experimental. I have
successfully run the full test suite with this option turned on, the name can now be
simply "mysql_bind_type_guessing".
CAVEAT: Even though you can insert an integer value into a character column, if this
column is indexed, if you query that column with the integer value not being quoted,
it will not use the index:
MariaDB [test]> explain select * from test where value0 = '3' \G
*************************** 1. row ***************************
id: 1
select_type: SIMPLE
table: test
type: ref possible_keys: value0
key: value0
key_len: 13
ref: const
rows: 1
Extra: Using index condition 1 row in set (0.00 sec)
MariaDB [test]> explain select * from test where value0 = 3
-> \G *************************** 1. row ***************************
id: 1
select_type: SIMPLE
table: test
type: ALL possible_keys: value0
key: NULL
key_len: NULL
ref: NULL
rows: 6
Extra: Using where 1 row in set (0.00 sec)
See bug: https://rt.cpan.org/Ticket/Display.html?id=43822
"mysql_bind_type_guessing" can be turned on via
- through DSN
my $dbh= DBI->connect('DBI:mysql:test', 'username', 'pass',
{ mysql_bind_type_guessing => 1})
- OR after handle creation
$dbh->{mysql_bind_type_guessing} = 1;
mysql_bind_comment_placeholders
This attribute causes the driver (emulated prepare statements) will cause any
placeholders in comments to be bound. This is not correct prepared statement behavior,
but some developers have come to depend on this behavior, so I have made it available
in 4.015
mysql_no_autocommit_cmd
This attribute causes the driver to not issue 'set autocommit' either through explicit
or using mysql_autocommit(). This is particularly useful in the case of using MySQL
Proxy.
See the bug report:
https://rt.cpan.org/Public/Bug/Display.html?id=46308
"mysql_no_autocommit_cmd" can be turned on via
- through DSN
my $dbh= DBI->connect('DBI:mysql:test', 'username', 'pass',
{ mysql_no_autocommit_cmd => 1})
- OR after handle creation
$dbh->{mysql_no_autocommit_cmd} = 1;
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 successful 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'} - 1;
for my $i ( 0..$numFields ) {
printf("%s%s", $i ? "," : "", $$names[$i]);
}
print "\n";
while (my $ref = $sth->fetchrow_arrayref) {
for my $i ( 0..$numFields ) {
printf("%s%s", $i ? "," : "", $$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 $dbh in this case!)
mysql_is_blob
Reference to an array of boolean values; TRUE indicates, that the respective column is
a blob. This attribute is valid for MySQL only.
mysql_is_key
Reference to an array of boolean values; TRUE indicates, that the respective column is
a key. This is valid for MySQL only.
mysql_is_num
Reference to an array of boolean values; TRUE indicates, that the respective column
contains numeric values.
mysql_is_pri_key
Reference to an array of boolean values; TRUE indicates, that the respective column is
a primary key.
mysql_is_auto_increment
Reference to an array of boolean values; TRUE indicates that the respective column is
an AUTO_INCREMENT column. This is only valid for MySQL.
mysql_length
mysql_max_length
A reference to an array of maximum column sizes. The max_length is the maximum
physically present in the result table, length gives the theoretically possible
maximum. max_length is valid for MySQL only.
mysql_clientinfo
List information of the MySQL client library that DBD::mysql was built against:
print "$dbh->{mysql_clientinfo}\n";
5.2.0-MariaDB
mysql_clientversion
print "$dbh->{mysql_clientversion}\n";
50200
mysql_serverversion
print "$dbh->{mysql_serverversion}\n";
50200
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 meaningful 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.
mysql_warning_count
The number of warnings generated during execution of the SQL statement. This
attribute is available on both statement handles and database handles.
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.
MULTIPLE RESULT SETS
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 someproc() 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}-1) {
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
snippets will be added in the future.
Issues with Multiple result sets
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.
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.
ASYNCHRONOUS QUERIES
You can make a single asynchronous query per MySQL connection; this allows you to submit a
long-running query to the server and have an event loop inform you when it's ready. An
asynchronous query is started by either setting the 'async' attribute to a true value in
the "do" in DBI method, or in the "prepare" in DBI method. Statements created with
'async' set to true in prepare always run their queries asynchronously when "execute" in
DBI is called. The driver also offers three additional methods: "mysql_async_result",
"mysql_async_ready", and "mysql_fd". "mysql_async_result" returns what do or execute
would have; that is, the number of rows affected. "mysql_async_ready" returns true if
"mysql_async_result" will not block, and zero otherwise. They both return "undef" if that
handle is not currently running an asynchronous query. "mysql_fd" returns the file
descriptor number for the MySQL connection; you can use this in an event loop.
Here's an example of how to use the asynchronous query interface:
use feature 'say';
$dbh->do('SELECT SLEEP(10)', { async => 1 });
until($dbh->mysql_async_ready) {
say 'not ready yet!';
sleep 1;
}
my $rows = $dbh->mysql_async_result;
INSTALLATION
Windows users may skip this section and pass over to WIN32 INSTALLATION below. Others, go
on reading.
Environment Variables
For ease of use, you can now set environment variables for DBD::mysql installation. You
can set any or all of the options, and export them by putting them in your .bashrc or the
like:
export DBD_MYSQL_CFLAGS=-I/usr/local/mysql/include/mysql
export DBD_MYSQL_LIBS="-L/usr/local/mysql/lib/mysql -lmysqlclient"
export DBD_MYSQL_EMBEDDED=
export DBD_MYSQL_CONFIG=mysql_config
export DBD_MYSQL_NOCATCHSTDERR=0
export DBD_MYSQL_NOFOUNDROWS=0
export DBD_MYSQL_SSL=
export DBD_MYSQL_TESTDB=test
export DBD_MYSQL_TESTHOST=localhost
export DBD_MYSQL_TESTPASSWORD=s3kr1+
export DBD_MYSQL_TESTPORT=3306
export DBD_MYSQL_TESTUSER=me
The most useful may be the host, database, port, socket, user, and password.
Installation will first look to your mysql_config, and then your environment variables,
and then it will guess with intelligent defaults.
Installing with CPAN
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.
I recommend trying automatic installation via the CPAN module. Try
cpan
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 DBD::mysql
Manual Installation
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
L<https://metacpan.org>
The following modules are required
DBI
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 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.
MARIADB NATIVE CLIENT INSTALLATION
The MariaDB native client is another option for connecting to a MySQL database licensed
LGPL 2.1. To build DBD::mysql against this client, you will first need to build the
client. Generally, this is done with the following:
cd path/to/src/mariadb-native-client
cmake -G "Unix Makefiles'
make
sudo make install
Once the client is built and installed, you can build DBD::mysql against it:
perl Makefile.PL --testuser=xxx --testpassword=xxx --testsocket=/path/to//mysqld.sock --mysql_config=/usr/local/bin/mariadb_config
make
make test
make install
WIN32 INSTALLATION
If you are using ActivePerl, you may use ppm to install DBD-mysql.
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/
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:
- 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 CMD.exe 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 flavor 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
AUTHORS
Originally, there was a non-DBI driver, Mysql, which was much like PHP drivers such as
mysql and mysqli. The Mysql module was originally written by Andreas Koenig
<koenig@kulturbox.de> who still, to this day, contributes patches to DBD::mysql. An
emulated version of Mysql was provided to DBD::mysql from Jochen Wiedmann, but eventually
deprecated as it was another bundle of code to maintain.
The first incarnation of DBD::mysql was developed by Alligator Descartes, who was also
aided and abetted by Gary Shea, Andreas Koenig and Tim Bunce.
The current incarnation of DBD::mysql was written by Jochen Wiedmann, then numerous
changes and bug-fixes were added by Rudy Lippan. Next, prepared statement support was
added by Patrick Galbraith and Alexy Stroganov (who also soleley added embedded server
support).
For the past nine years DBD::mysql has been maintained by Patrick Galbraith
(patg@patg.net), and recently with the great help of Michiel Beijen
(michiel.beijen@gmail.com), along with the entire community of Perl developers who keep
sending patches to help continue improving DBD::mysql
CONTRIBUTIONS
Anyone who desires to contribute to this project is encouraged to do so. Currently, the
source code for this project can be found at Github:
<https://github.com/perl5-dbi/DBD-mysql/>
Either fork this repository and produce a branch with your changeset that the maintainer
can merge to his tree, or create a diff with git. The maintainer is more than glad to take
contributions from the community as many features and fixes from DBD::mysql have come from
the community.
COPYRIGHT
This module is
• Large Portions Copyright (c) 2004-2013 Patrick Galbraith
• Large Portions Copyright (c) 2004-2006 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
LICENSE
This module is released under the same license as Perl itself. See
<http://www.perl.com/perl/misc/Artistic.html> for details.
MAILING LIST SUPPORT
This module is maintained and supported on a mailing list, dbi-users.
To subscribe to this list, send an email to
dbi-users-subscribe@perl.org
Mailing list archives are at
<http://groups.google.com/group/perl.dbi.users?hl=en&lr=>
ADDITIONAL DBI INFORMATION
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
Information on DBD::mysql specifically can be gained by typing:
perldoc DBD::mysql
(this will display the document you're currently reading)
BUG REPORTING, ENHANCEMENT/FEATURE REQUESTS
Please report bugs, including all the information needed such as DBD::mysql version, MySQL
version, OS type/version, etc to this link:
<https://rt.cpan.org/Dist/Display.html?Name=DBD-mysql>
Note: until recently, MySQL/Sun/Oracle responded to bugs and assisted in fixing bugs which
many thanks should be given for their help! This driver is outside the realm of the
numerous components they support, and the maintainer and community solely support
DBD::mysql