The character set determines what characters are allowed in identifiers. The collation determines how strings are sorted by the ORDER BY and GROUP BY clauses of the SELECT statement.

By default, MySQL uses the latin1 (cp1252 West European) character set and the latin1_swedish_ci collation that sorts according to Swedish/Finnish rules. These defaults are suitable for the United States and most of Western Europe.

All MySQL binary distributions are compiled with --with-extra-charsets=complex. This adds code to all standard programs that enables them to handle latin1 and all multi-byte character sets within the binary. Other character sets are loaded from a character-set definition file when needed.

You can change the default server character set and collation with the --character-set-server and --collation-server options when you start the server. The collation must be a legal collation for the default character set. (Use the SHOW COLLATION statement to determine which collations are available for each character set.) See Section 5.1.2, “Server Command Options”.

The character sets available depend on the --with-charset=charset_name and --with-extra-charsets=list-of-charsets | complex | all | none options to configure, and the character set configuration files listed in SHAREDIR/charsets/Index. See Section 2.10.2, “Typical configure Options”.

When a client connects to the server, it sends the name of the character set that it wants to use. The server uses the name to set various character set system variables for the connection. For more information, see Section 9.1.4, “Connection Character Sets and Collations”.

Within C programs, you should use mysql_real_escape_string() when escaping strings for an SQL query. mysql_real_escape_string() is identical to the old mysql_escape_string() function, except that it takes the MYSQL connection handler as the first parameter so that the appropriate character set can be taken into account when escaping characters.

If the client is compiled with paths that differ from where the server is installed and the user who configured MySQL did not include all character sets in the MySQL binary, you must tell the client where it can find the additional character sets it needs if the server runs with a different character set from the client. You can do this by specifying a --character-sets-dir option to indicate the path to the directory in which the dynamic MySQL character sets are stored. For example, you can put the following in an option file:

[client]
character-sets-dir=/usr/local/mysql/share/mysql/charsets

You can force the client to use specific character set as follows:

[client]
default-character-set=charset_name

This is normally unnecessary, however.