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DBD::mysql(3) |
User Contributed Perl Documentation |
DBD::mysql(3) |
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 DBD::mysql::INSTALL. 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
DBD::mysql::INSTALL 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 <http://backronym.fail/> and The Riddle
<http://riddle.link/> 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_server_pubkey
- Path to the RSA public key of the server. This is used for the
sha256_password and caching_sha2_password authentication plugins.
- mysql_get_server_pubkey
- Setting "mysql_get_server_pubkey" to
true requests the public RSA key of the server.
- 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 = $dbh->{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 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 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_gtids
- Returns GTID(s) if GTID session tracking is ensabled in the server via
session_track_gtids.
- 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 yes, since MySQL 5.5 it is.
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 was not created with 'async' set to true or if an asynchronous
query was not started yet. "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;
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?hl=en&lr=>
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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