10.3.1 Collation Naming Conventions
MySQL collation names follow these conventions:
A collation name starts with the name of the character set with which it is associated, generally followed by one or more suffixes indicating other collation characteristics. For example,
latin1_swedish_ciare collations for the
latin1character sets, respectively. The
binarycharacter set has a single collation, also named
binary, with no suffixes.
A language-specific collation includes a language name. For example,
utf8_hungarian_cisort characters for the
utf8character set using the rules of Turkish and Hungarian, respectively.
Collation suffixes indicate whether a collation is case-sensitive, accent-sensitive, or kana-sensitive (or some combination thereof), or binary. The following table shows the suffixes used to indicate these characteristics.
Table 10.1 Collation Suffix Meanings
For nonbinary collation names that do not specify accent sensitivity, it is determined by case sensitivity. If a collation name does not contain
_ciin the name implies
_csin the name implies
_as. For example,
latin1_general_ciis explicitly case-insensitive and implicitly accent-insensitive, and
latin1_general_csis explicitly case-sensitive and implicitly accent-sensitive.
binarycollation of the
binarycharacter set, comparisons are based on numeric byte values. For the
_bincollation of a nonbinary character set, comparisons are based on numeric character code values, which differ from byte values for multibyte characters. For information about the differences between the
binarycollation of the
binarycharacter set and the
_bincollations of nonbinary character sets, see Section 10.8.5, “The binary Collation Compared to _bin Collations”.
Collation names for Unicode character sets may include a version number to indicate the version of the Unicode Collation Algorithm (UCA) on which the collation is based. UCA-based collations without a version number in the name use the version-4.0.0 UCA weight keys. For example:
utf8_unicode_520_ciis based on UCA 5.2.0 weight keys (http://www.unicode.org/Public/UCA/5.2.0/allkeys.txt ).
utf8_unicode_ci(with no version named) is based on UCA 4.0.0 weight keys (http://www.unicode.org/Public/UCA/4.0.0/allkeys-4.0.0.txt ).
For Unicode character sets, the
collations preserve the pre-5.1.24 ordering of the original
collations and permit upgrades for tables created before MySQL 5.1.24 (Bug #27877).