Every database has a database character set and a database
collation. The CREATE DATABASE
and ALTER DATABASE statements
have optional clauses for specifying the database character
set and collation:
CREATE DATABASEdb_name[[DEFAULT] CHARACTER SETcharset_name] [[DEFAULT] COLLATEcollation_name] ALTER DATABASEdb_name[[DEFAULT] CHARACTER SETcharset_name] [[DEFAULT] COLLATEcollation_name]
The keyword SCHEMA can be used instead of
DATABASE.
All database options are stored in a text file named
db.opt that can be found in the database
directory.
The CHARACTER SET and
COLLATE clauses make it possible to create
databases with different character sets and collations on the
same MySQL server.
Example:
CREATE DATABASE db_name CHARACTER SET latin1 COLLATE latin1_swedish_ci;
MySQL chooses the database character set and database collation in the following manner:
If both CHARACTER SET
and
charset_nameCOLLATE
are
specified, character set
collation_namecharset_name and collation
collation_name are used.
If CHARACTER SET
is
specified without charset_nameCOLLATE, character
set charset_name and its
default collation are used. To see the default collation
for each character set, use the SHOW
CHARACTER SET statement.
If COLLATE
is
specified without collation_nameCHARACTER SET, the
character set associated with
collation_name and collation
collation_name are used.
Otherwise (neither CHARACTER SET nor
COLLATE is specified), the server
character set and server collation are used.
The character set and collation for the default database can
be determined from the values of the
character_set_database and
collation_database system
variables. The server sets these variables whenever the
default database changes. If there is no default database, the
variables have the same value as the corresponding
server-level system variables,
character_set_server and
collation_server.
To see the default character set and collation for a given database, use these statements:
USE db_name;
SELECT @@character_set_database, @@collation_database;
Alternatively, to display the values without changing the default database:
SELECT DEFAULT_CHARACTER_SET_NAME, DEFAULT_COLLATION_NAME
FROM INFORMATION_SCHEMA.SCHEMATA WHERE SCHEMA_NAME = 'db_name';
The database character set and collation affect these aspects of server operation:
For CREATE TABLE
statements, the database character set and collation are
used as default values for table definitions if the table
character set and collation are not specified. To override
this, provide explicit CHARACTER SET
and COLLATE table options.
For LOAD DATA statements
that include no CHARACTER SET clause,
the server uses the character set indicated by the
character_set_database
system variable to interpret the information in the file.
To override this, provide an explicit CHARACTER
SET clause.
For stored routines (procedures and functions), the
database character set and collation in effect at routine
creation time are used as the character set and collation
of character data parameters for which the declaration
includes no CHARACTER SET or
COLLATE attribute. To override this,
provide explicit CHARACTER SET and
COLLATE attributes.