DBD::mysql(3) User Contributed Perl Documentation DBD::mysql(3)
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 noone ever requested them. :-)
In what follows we first discuss the use of DBD::mysql, because this is
what you will need the most. For installation, see the sections on
INSTALLATION, and "WIN32 INSTALLATION" below. See EXAMPLE for a simple
example above.
From perl you activate the interface with the statement
use DBI;
After that you can connect to multiple MySQL database servers and send
multiple queries to any of them via a simple object oriented interface.
Two types of objects are available: database handles and statement
handles. Perl returns a database handle to the connect method like so:
$dbh = DBI->connect("DBI:mysql:database=$db;host=$host",
$user, $password, {RaiseError => 1});
Once you have connected to a database, you can can execute SQL
statements with:
my $query = sprintf("INSERT INTO foo VALUES (%d, %s)",
$number, $dbh->quote("name"));
$dbh->do($query);
See DBI(3) for details on the quote and do methods. An alternative
approach is
$dbh->do("INSERT INTO foo VALUES (?, ?)", undef,
$number, $name);
in which case the quote method is executed automatically. See also the
bind_param method in DBI(3). See "DATABASE HANDLES" below for more
details on database handles.
If you want to retrieve results, you need to create a so-called
statement handle with:
$sth = $dbh->prepare("SELECT * FROM $table");
$sth->execute();
This statement handle can be used for multiple things. First of all you
can retreive a row of data:
my $row = $sth->fetchrow_hashref();
If your table has columns ID and NAME, then $row will be hash ref with
keys ID and NAME. See "STATEMENT HANDLES" below for more details on
statement handles.
But now for a more formal approach:
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_timeout=##", 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 seperated 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
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.
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. (That's why
mysql_store_result is the default.)
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 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 $dbh in this
case!)
mysql_is_blob
Reference to an array of boolean values; TRUE indicates, that the
respective column is a blob. This attribute is valid for MySQL
only.
mysql_is_key
Reference to an array of boolean values; TRUE indicates, that the
respective column is a key. This is valid for MySQL only.
mysql_is_num
Reference to an array of boolean values; TRUE indicates, that the
respective column contains numeric values.
mysql_is_pri_key
Reference to an array of boolean values; TRUE indicates, that the
respective column is a primary key.
mysql_is_auto_increment
Reference to an array of boolean values; TRUE indicates that the
respective column is an AUTO_INCREMENT column. This is only valid
for MySQL.
mysql_length
mysql_max_length
A reference to an array of maximum column sizes. The max_length is
the maximum physically present in the result table, length gives
the theoretically possible maximum. max_length is valid for MySQL
only.
mysql_clientinfo
List information of the MySQL client library that DBD::mysql was
built against:
print "$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 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.
mysql_warning_count
The number of warnings generated during execution of the SQL
statement.
TRANSACTION SUPPORT
Beginning with DBD::mysql 2.0416, transactions are supported. The
transaction support works as follows:
o By default AutoCommit mode is on, following the DBI specifications.
o 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.
o 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:
o You should never change the server variable autocommit manually,
unless you are ignoring DBI's transaction support.
o 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!
}
o 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.
o 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.
o 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 somproc() deterministic
begin
declare a,b,c,d int;
set a=1;
set b=2;
set c=3;
set d=4;
select a, b, c, d;
select d, c, b, a;
select b, a, c, d;
select c, b, d, a;
end") or print $DBI::errstr;
$sth=$dbh->prepare('call someproc()') ||
die $DBI::err.": ".$DBI::errstr;
$sth->execute || die DBI::err.": ".$DBI::errstr; $rowset=0;
do {
print "\nRowset ".++$i."\n---------------------------------------\n\n";
foreach $colno (0..$sth->{NUM_OF_FIELDS}) {
print $sth->{NAME}->[$colno]."\t";
}
print "\n";
while (@row= $sth->fetchrow_array()) {
foreach $field (0..$#row) {
print $row[$field]."\t";
}
print "\n";
}
} until (!$sth->more_results)
For more examples, please see the eg/ directory. This is where helpful
DBD::mysql code snippits will be added in the future.
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 truthy 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.
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
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 search
http://search.cpan.org/
The following modules are required
DBI
Data::ShowTable
DBD::mysql
Then enter the following commands (note - versions are just examples):
gzip -cd DBI-(version).tar.gz | tar xf -
cd DBI-(version)
perl Makefile.PL
make
make test
make install
cd ..
gzip -cd Data-ShowTable-(version).tar.gz | tar xf -
cd Data-ShowTable-3.3
perl Makefile.PL
make
make install
cd ..
gzip -cd DBD-mysql-(version)-tar.gz | tar xf -
cd DBD-mysql-(version)
perl Makefile.PL
make
make test
make install
During "perl Makefile.PL" you will be prompted some questions. Other
questions are the directories with header files and libraries. For
example, of your file mysql.h is in /usr/include/mysql/mysql.h, then
enter the header directory /usr, likewise for
/usr/lib/mysql/libmysqlclient.a or /usr/lib/libmysqlclient.so.
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 = $_;
- 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
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 KieXXnig <koenig AT 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
KieXXnig 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 soley added embedded server support).
For the past seven years DBD::mysql has been maintained by Patrick
Galbraith (patg AT patg.net) along with the entire community of Perl
developers who keep sending patches and making Patrick's job easier.
CONTRIBUTIONS
Anyone who desires to contribute to this project is encouraged to do
so. Currently, the sourcecode for this project can be found at Github:
git://github.com/CaptTofu/DBD-mysql.git
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) 2004-2010 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 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, dbi-users.
To subscribe to this list, send and email to
dbi-users-subscribe AT perl.org
Mailing list archives are at
http://groups.google.com/group/perl.dbi.users?hl=en&lr=
Also, the main DBI site is at
http://dbi.perl.org/
And source:
git://github.com/CaptTofu/DBD-mysql.git
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 the DBD::mysql specifically can be gained by typing:
perldoc DBD::mysql
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:
http://rt.cpan.org
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
POD ERRORS
Hey! The above document had some coding errors, which are explained
below:
Around line 1315:
'=item' outside of any '=over'
Around line 1464:
You forgot a '=back' before '=head1'
Around line 1727:
You forgot a '=back' before '=head1'
Around line 2070:
Non-ASCII character seen before =encoding in 'KieXXnig'. Assuming
UTF-8
perl v5.16.3 2013-04-12 DBD::mysql(3)
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