In MySQL, the
sjis character set
corresponds to the
Shift_JIS character set
defined by IANA, which supports JIS X0201 and JIS X0208
However, the meaning of “SHIFT JIS” as a
descriptive term has become very vague and it often includes
the extensions to
Shift_JIS that are
defined by various vendors.
For example, “SHIFT JIS” used in Japanese Windows
environments is a Microsoft extension of
Shift_JIS and its exact name is
Microsoft Windows Codepage : 932 or
cp932. In addition to the characters
cp932 supports extension characters such as
NEC special characters, NEC selected—IBM extended
characters, and IBM selected characters.
Many Japanese users have experienced problems using these extension characters. These problems stem from the following factors:
MySQL automatically converts character sets.
Character sets are converted using Unicode (
sjischaracter set does not support the conversion of these extension characters.
There are several conversion rules from so-called “SHIFT JIS” to Unicode, and some characters are converted to Unicode differently depending on the conversion rule. MySQL supports only one of these rules (described later).
cp932 character set is designed
to solve these problems.
Because MySQL supports character set conversion, it is
important to separate IANA
cp932 into two different character sets
because they provide different conversion rules.
cp932 character set differs from
sjis in the following ways:
cp932supports NEC special characters, NEC selected—IBM extended characters, and IBM selected characters.
cp932characters have two different code points, both of which convert to the same Unicode code point. When converting from Unicode back to
cp932, one of the code points must be selected. For this “round trip conversion,” the rule recommended by Microsoft is used. (See http://support.microsoft.com/kb/170559/EN-US/.)
The conversion rule works like this:
If the character is in both JIS X 0208 and NEC special characters, use the code point of JIS X 0208.
If the character is in both NEC special characters and IBM selected characters, use the code point of NEC special characters.
If the character is in both IBM selected characters and NEC selected—IBM extended characters, use the code point of IBM extended characters.
The table shown at https://msdn.microsoft.com/en-us/goglobal/cc305152.aspx provides information about the Unicode values of
cp932table entries with characters under which a four-digit number appears, the number represents the corresponding Unicode (
ucs2) encoding. For table entries with an underlined two-digit value appears, there is a range of
cp932character values that begin with those two digits. Clicking such a table entry takes you to a page that displays the Unicode value for each of the
cp932characters that begin with those digits.
The following links are of special interest. They correspond to the encodings for the following sets of characters:
NEC special characters (lead byte
NEC selected—IBM extended characters (lead byte
IBM selected characters (lead byte
https://msdn.microsoft.com/en-us/goglobal/gg671839 https://msdn.microsoft.com/en-us/goglobal/gg671840 https://msdn.microsoft.com/en-us/goglobal/gg671841
cp932supports conversion of user-defined characters in combination with
eucjpms, and solves the problems with
ujisconversion. For details, please refer to http://www.sljfaq.org/afaq/encodings.html.
For some characters, conversion to and from
ucs2 is different for
following tables illustrate these differences.