DBD::mysql - MySQL driver for the Perl5 Database Interface (DBI)
use DBI;
my $dsn = "DBI:mysql:database=$database;host=$hostname;port=$port";
my $dbh = DBI->connect($dsn, $user, $password);
my $sth = $dbh->prepare(
'SELECT id, first_name, last_name FROM authors WHERE last_name = ?')
or die "prepare statement failed: $dbh->errstr()";
$sth->execute('Eggers') or die "execution failed: $dbh->errstr()";
print $sth->rows . " rows found.\n";
while (my $ref = $sth->fetchrow_hashref()) {
print "Found a row: id = $ref->{'id'}, fn = $ref->{'first_name'}\n";
}
$sth->finish;
#!/usr/bin/perl
use strict;
use warnings;
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 (recommended!)
$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();
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
separate document the DBD::mysql::INSTALL manpage.
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:
- 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);
The database is not a required attribute, but please note that MySQL
has no such thing as a default database. If you don't specify the database
at connection time your active database will be null and you'd need to prefix
your tables with the database name; i.e. 'SELECT * FROM mydb.mytable'.
This is similar to the behavior of the mysql command line client. Also,
'SELECT DATABASE()' will return the current database active for the handle.
- 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).
When connecting to a MySQL Server with IPv6, a bracketed IPv6 address should be used.
Example DSN:
my $dsn = "DBI:mysql:;host=[1a12:2800:6f2:85::f20:8cf];port=3306";
- 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
-
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_skip_secure_auth
-
This option is for older mysql databases that don't have secure auth set.
- 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
-
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
server and enforce SSL encryption. A false value (which is default)
disable SSL encryption with the MySQL server.
When enabling SSL encryption you should set also other SSL options,
at least mysql_ssl_ca_file or mysql_ssl_ca_path.
mysql_ssl=1 mysql_ssl_verify_server_cert=1 mysql_ssl_ca_file=/path/to/ca_cert.pem
This means that your communication with the server will be encrypted.
Please note that this can only work if you enabled SSL when compiling
DBD::mysql; this is the default starting version 4.034.
See the DBD::mysql::INSTALL manpage for more details.
- mysql_ssl_ca_file
-
The path to a file in PEM format that contains a list of trusted SSL
certificate authorities.
When set MySQL server certificate is checked that it is signed by some
CA certificate in the list. Common Name value is not verified unless
mysql_ssl_verify_server_cert is enabled.
- mysql_ssl_ca_path
-
The path to a directory that contains trusted SSL certificate authority
certificates in PEM format.
When set MySQL server certificate is checked that it is signed by some
CA certificate in the list. Common Name value is not verified unless
mysql_ssl_verify_server_cert is enabled.
Please note that this option is supported only if your MySQL client was
compiled with OpenSSL library, and not with default yaSSL library.
- mysql_ssl_verify_server_cert
-
Checks the server's Common Name value in the certificate that the server
sends to the client. The client verifies that name against the host name
the client uses for connecting to the server, and the connection fails if
there is a mismatch. For encrypted connections, this option helps prevent
man-in-the-middle attacks.
Verification of the host name is disabled by default.
- mysql_ssl_client_key
-
The name of the SSL key file in PEM format to use for establishing
a secure connection.
- mysql_ssl_client_cert
-
The name of the SSL certificate file in PEM format to use for
establishing a secure connection.
- mysql_ssl_cipher
-
A list of permissible ciphers to use for connection encryption. If no
cipher in the list is supported, encrypted connections will not work.
mysql_ssl_cipher=AES128-SHA
mysql_ssl_cipher=DHE-RSA-AES256-SHA:AES128-SHA
- mysql_ssl_optional
-
Setting
mysql_ssl_optional to true disables strict SSL enforcement
and makes SSL connection optional. This option opens security hole
for man-in-the-middle attacks. Default value is false which means
that mysql_ssl set to true enforce SSL encryption.
This option was introduced in 4.043 version of DBD::mysql. Due to
The BACKRONYM and The Riddle
vulnerabilities in libmysqlclient library, enforcement of SSL
encryption was not possbile and therefore mysql_ssl_optional=1
was effectively set for all DBD::mysql versions prior to 4.043.
Starting with 4.043, DBD::mysql with mysql_ssl=1 could refuse
connection to MySQL server if underlaying libmysqlclient library is
vulnerable. Option mysql_ssl_optional can be used to make SSL
connection vulnerable.
- mysql_local_infile
-
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
-
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.
- mysql_server_prepare
-
This option is used to enable server side prepared statements.
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 }
);
or:
$dbh = DBI->connect(
"DBI:mysql:database=test;host=localhost",
"",
"",
{ RaiseError => 1, AutoCommit => 1, mysql_server_prepare => 1 }
);
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
Please note that mysql server cannot prepare or execute some prepared statements.
In this case DBD::mysql fallbacks to normal non-prepared statement and tries again.
- mysql_server_prepare_disable_fallback
-
This option disable fallback to normal non-prepared statement when mysql server
does not support execution of current statement as prepared.
Useful when you want to be sure that statement is going to be executed as
server side prepared. Error message and code in case of failure is propagated
back to DBI.
- 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";
- mysql_conn_attrs
-
The option <mysql_conn_attrs> is a hash of attribute names and values which can be
used to send custom connection attributes to the server. Some attributes like
'_os', '_platform', '_client_name' and '_client_version' are added by libmysqlclient
and 'program_name' is added by DBD::mysql.
You can then later read these attributes from the performance schema tables which
can be quite helpful for profiling your database or creating statistics.
You'll have to use a MySQL 5.6 server and libmysqlclient or newer to leverage this
feature.
my $dbh= DBI->connect($dsn, $user, $password,
{ AutoCommit => 0,
mysql_conn_attrs => {
foo => 'bar',
wiz => 'bang'
},
});
Now you can select the results from the performance schema tables. You can do this
in the same session, but also afterwards. It can be very useful to answer questions
like 'which script sent this query?'.
my $results = $dbh->selectall_hashref(
'SELECT * FROM performance_schema.session_connect_attrs',
'ATTR_NAME'
);
This returns:
$result = {
'foo' => {
'ATTR_VALUE' => 'bar',
'PROCESSLIST_ID' => '3',
'ATTR_NAME' => 'foo',
'ORDINAL_POSITION' => '6'
},
'wiz' => {
'ATTR_VALUE' => 'bang',
'PROCESSLIST_ID' => '3',
'ATTR_NAME' => 'wiz',
'ORDINAL_POSITION' => '3'
},
'program_name' => {
'ATTR_VALUE' => './foo.pl',
'PROCESSLIST_ID' => '3',
'ATTR_NAME' => 'program_name',
'ORDINAL_POSITION' => '5'
},
'_client_name' => {
'ATTR_VALUE' => 'libmysql',
'PROCESSLIST_ID' => '3',
'ATTR_NAME' => '_client_name',
'ORDINAL_POSITION' => '1'
},
'_client_version' => {
'ATTR_VALUE' => '5.6.24',
'PROCESSLIST_ID' => '3',
'ATTR_NAME' => '_client_version',
'ORDINAL_POSITION' => '7'
},
'_os' => {
'ATTR_VALUE' => 'osx10.8',
'PROCESSLIST_ID' => '3',
'ATTR_NAME' => '_os',
'ORDINAL_POSITION' => '0'
},
'_pid' => {
'ATTR_VALUE' => '59860',
'PROCESSLIST_ID' => '3',
'ATTR_NAME' => '_pid',
'ORDINAL_POSITION' => '2'
},
'_platform' => {
'ATTR_VALUE' => 'x86_64',
'PROCESSLIST_ID' => '3',
'ATTR_NAME' => '_platform',
'ORDINAL_POSITION' => '4'
}
};
- 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");
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 = $dbh->{'mysql_thread_id'};
These correspond to mysql_errno(), mysql_error(), mysql_get_host_info(),
mysql_info(), mysql_insert_id(), mysql_get_proto_info(),
mysql_get_server_info(), mysql_stat() and mysql_thread_id(),
respectively.
- mysql_clientinfo
-
List information of the MySQL client library that DBD::mysql was built
against:
print "$dbh->{mysql_clientinfo}\n";
5.2.0-MariaDB
- mysql_clientversion
-
print "$dbh->{mysql_clientversion}\n";
50200
- mysql_serverversion
-
print "$dbh->{mysql_serverversion}\n";
50200
- mysql_dbd_stats
-
$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 attributes of database
handles (read/write):
- 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>.
$dbh->{mysql_auto_reconnect} = 1;
or
my $dbh = DBI->connect($dsn, $user, $password, {
mysql_auto_reconnect => 1,
});
Note that if you are using a module or framework that performs reconnections
for you (for example the DBIx::Connector manpage 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 via the DSN:
$dbh = DBI->connect("DBI:mysql:test;mysql_use_result=1", "root", "");
You can also set it after creation of the database handle:
$dbh->{mysql_use_result} = 0; # disable
$dbh->{mysql_use_result} = 1; # enable
You can also set or unset the mysql_use_result setting on your statement
handle, when creating the statement handle or after it has been created.
See STATEMENT HANDLES.
- 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 for more
information the chapter on character set support in the MySQL manual:
http://dev.mysql.com/doc/refman/5.7/en/charset.html
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.
- mysql_enable_utf8mb4
-
This is similar to mysql_enable_utf8, but is capable of handling 4-byte
UTF-8 characters.
- 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 when creating the database
handle:
my $dbh = DBI->connect('DBI:mysql:test', 'username', 'pass',
{ mysql_no_autocommit_cmd => 1});
or using an existing database handle:
$dbh->{mysql_no_autocommit_cmd} = 1;
- ping
-
This can be used to send a ping to the server.
$rc = $dbh->ping();
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 otherwise. The most important exception
is the mysql_use_result attribute, which 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 = $dbh->prepare($sql);
$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") ||
die "Error:" . $dbh->errstr . "\n";
$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
-
If the statement you executed performs an INSERT, and there is an AUTO_INCREMENT
column in the table you inserted in, this attribute holds the value stored into
the AUTO_INCREMENT column, if that value is automatically generated, by
storing NULL or 0 or was specified as an explicit value.
Typically, you'd access the value via $sth->{mysql_insertid}. The value can
also be accessed via $dbh->{mysql_insertid} but this can easily
produce incorrect results in case one database handle is shared.
- 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 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.
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 ROLLBACK and COMMIT, 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:
DBD::mysql supports multiple result sets, thanks to Guy Harrison!
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)
Please be aware there could be issues 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.
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.
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 DBI/do method,
or in the DBI/prepare method. Statements created with 'async' set to
true in prepare always run their queries asynchronously when DBI/execute
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;
See the DBD::mysql::INSTALL manpage.
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 König <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 König 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 solely 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
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.
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
This module is released under the same license as Perl itself. See
http://www.perl.com/perl/misc/Artistic.html for details.
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
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)
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
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