MySQL 5.5 Release Notes
[+/-]
- 10.1.10.1 The ucs2 Character Set (UCS-2 Unicode Encoding)
- 10.1.10.2 The utf16 Character Set (UTF-16 Unicode Encoding)
- 10.1.10.3 The utf32 Character Set (UTF-32 Unicode Encoding)
- 10.1.10.4 The utf8 Character Set (3-Byte UTF-8 Unicode Encoding)
- 10.1.10.5 The utf8mb3 Character Set (Alias for utf8)
- 10.1.10.6 The utf8mb4 Character Set (4-Byte UTF-8 Unicode Encoding)
The initial implementation of Unicode support (in MySQL 4.1) included two character sets for storing Unicode data:
ucs2, the UCS-2 encoding of the Unicode character set using 16 bits per character.utf8, a UTF-8 encoding of the Unicode character set using one to three bytes per character.
These two character sets support the characters from the Basic Multilingual Plane (BMP) of Unicode Version 3.0. BMP characters have these characteristics:
Their code values are between 0 and 65535 (or
U+0000..U+FFFF).They can be encoded with a fixed 16-bit word, as in
ucs2.They can be encoded with 8, 16, or 24 bits, as in
utf8.They are sufficient for almost all characters in major languages.
Characters not supported by the aforementioned character sets
include supplementary characters that lie outside the BMP.
Characters outside the BMP compare as REPLACEMENT CHARACTER and
convert to '?' when converted to a Unicode
character set.
As of MySQL 5.5.3, Unicode support includes supplementary characters, which requires new character sets that have a broader range (including non-BMP characters) and therefore take more space. The following table shows a brief feature comparison of previous and current Unicode support.
| Before MySQL 5.5 | MySQL 5.5 and up |
|---|---|
| All Unicode 3.0 characters | All Unicode 5.0 and 6.0 characters |
| No supplementary characters | With supplementary characters |
ucs2 character set, BMP only | No change |
utf8 character set for up to three bytes, BMP only | No change |
New utf8mb4 character set for up to four bytes, BMP
or supplemental | |
New utf16 character set, BMP or supplemental | |
New utf32 character set, BMP or supplemental |
These changes are upward compatible. If you want to use the new
character sets, there are potential incompatibility issues for
your applications; see
Section 10.1.11, “Upgrading from Previous to Current Unicode Support”. That section also
describes how to convert tables from utf8 to
the (4-byte) utf8mb4 character set, and what
constraints may apply in doing so.
MySQL 5.5 supports these Unicode character sets:
ucs2, the UCS-2 encoding of the Unicode character set using 16 bits per character.utf16, the UTF-16 encoding for the Unicode character set; likeucs2but with an extension for supplementary characters.utf32, the UTF-32 encoding for the Unicode character set using 32 bits per character.utf8, a UTF-8 encoding of the Unicode character set using one to three bytes per character.utf8mb4, a UTF-8 encoding of the Unicode character set using one to four bytes per character.
ucs2 and utf8 support BMP
characters. utf8mb4,
utf16, and utf32 support
BMP and supplementary characters.
A similar set of collations is available for each Unicode
character set. For example, each has a Danish collation, the
names of which are ucs2_danish_ci,
utf16_danish_ci,
utf32_danish_ci,
utf8_danish_ci, and
utf8mb4_danish_ci. All Unicode collations are
listed at Section 10.1.14.1, “Unicode Character Sets”, which also
describes collation properties for supplementary characters.
Note that although many of the supplementary characters come from East Asian languages, what MySQL 5.5 adds is support for more Japanese and Chinese characters in Unicode character sets, not support for new Japanese and Chinese character sets.
The MySQL implementation of UCS-2, UTF-16, and UTF-32 stores characters in big-endian byte order and does not use a byte order mark (BOM) at the beginning of values. Other database systems might use little-endian byte order or a BOM. In such cases, conversion of values will need to be performed when transferring data between those systems and MySQL.
MySQL uses no BOM for UTF-8 values.
Client applications that need to communicate with the server
using Unicode should set the client character set accordingly;
for example, by issuing a SET NAMES 'utf8'
statement. ucs2, utf16,
and utf32 cannot be used as a client
character set, which means that they do not work for
SET NAMES or SET CHARACTER
SET. (See Section 10.1.4, “Connection Character Sets and Collations”.)
The following sections provide additional detail on the Unicode character sets in MySQL.
mysql --default-character-set=utf8 -uyour_username -p -h your_databasehost.your_domain.com your_database
If you get into trouble from a PHP-based web application, check the characterset configurations of these components:
1) the MySQL database
2) php.ini
3) httpd.conf
4) your server
but still get '?' for some special characters in your browser
(<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />),
try this:
after mysql_connect() , and mysql_select_db() add this lines:
mysql_query("SET NAMES utf8");
worked for me.
i tried first with the utf8_encode, but this only worked for äüöéè...
and so on, but not for kyrillic and other chars.
It turns out the problem was that my ODBC driver was version 3.5.1 and that's what caused the problem. Installing version 5.1 solved the problem.
http://dev.mysql.com/downloads/connector/odbc/
I have blogged about this here: http://blog.oneiroi.co.uk/mysql/mysql-forcing-utf-8-compliance-for-all-connections
Removing the need to use SET NAME in your PHP/ASP/Ruby/C++ code.