For applications that store data using the default MySQL
character set and collation (
latin1_swedish_ci), no special configuration
should be needed. If applications require data storage using a
different character set or collation, you can configure
character set information several ways:
Specify character settings per database. For example, applications that use one database might require
utf8, whereas applications that use another database might require
Specify character settings at server startup. This causes the server to use the given settings for all applications that do not make other arrangements.
Specify character settings at configuration time, if you build MySQL from source. This causes the server to use the given settings for all applications, without having to specify them at server startup.
When different applications require different character settings, the per-database technique provides a good deal of flexibility. If most or all applications use the same character set, specifying character settings at server startup or configuration time may be most convenient.
For the per-database or server-startup techniques, the settings control the character set for data storage. Applications must also tell the server which character set to use for client/server communications, as described in the following instructions.
The examples shown here assume use of the
utf8 character set and
Specify character settings per
database. To create a database such that its tables
will use a given default character set and collation for data
storage, use a
statement like this:
CREATE DATABASE mydb DEFAULT CHARACTER SET utf8 DEFAULT COLLATE utf8_general_ci;
Tables created in the database will use
utf8_general_ci by default for any
Applications that use the database should also configure their
connection to the server each time they connect. This can be
done by executing a
SET NAMES 'utf8'
statement after connecting. The statement can be used regardless
of connection method: The mysql client, PHP
scripts, and so forth.
In some cases, it may be possible to configure the connection to
use the desired character set some other way. For example, for
connections made using mysql, you can specify
command-line option to achieve the same effect as
For more information about configuring client connections, see Section 10.1.4, “Connection Character Sets and Collations”.
If you change the default character set or collation for a database, stored routines that use the database defaults must be dropped and recreated so that they use the new defaults. (In a stored routine, variables with character data types use the database defaults if the character set or collation are not specified explicitly. See Section 13.1.15, “CREATE PROCEDURE and CREATE FUNCTION Syntax”.)
Specify character settings at server
startup. To select a character set and collation at
server startup, use the
--collation-server options. For
example, to specify the options in an option file, include these
[mysqld] character-set-server=utf8 collation-server=utf8_general_ci
These settings apply server-wide and apply as the defaults for databases created by any application, and for tables created in those databases.
It is still necessary for applications to configure their
SET NAMES or
equivalent after they connect, as described previously. You
might be tempted to start the server with the
--init_connect="SET NAMES 'utf8'"
option to cause
SET NAMES to be
executed automatically for each client that connects. However,
this will yield inconsistent results because the
init_connect value is not
executed for users who have the
Specify character settings at MySQL
configuration time. To select a character set and
collation when you configure and build MySQL from source, use
DEFAULT_COLLATION options for
shell> cmake . -DDEFAULT_CHARSET=utf8 \ -DDEFAULT_COLLATION=utf8_general_ci
The resulting server uses
utf8_general_ci as the default for databases
and tables and for client connections. It is unnecessary to use
--collation-server to specify
those defaults at server startup. It is also unnecessary for
applications to configure their connection using
SET NAMES or equivalent after
they connect to the server.
Regardless of how you configure the MySQL character set for
application use, you must also consider the environment within
which those applications execute. If you will send statements
using UTF-8 text taken from a file that you create in an editor,
you should edit the file with the locale of your environment set
to UTF-8 so that the file encoding is correct and so that the
operating system handles it correctly. If you use the
mysql client from within a terminal window,
the window must be configured to use UTF-8 or characters may not
display properly. For a script that executes in a Web
environment, the script must handle character encoding properly
for its interaction with the MySQL server, and it must generate
pages that correctly indicate the encoding so that browsers know
how to display the content of the pages. For example, you can
<meta> tag within your
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />