10.1.8 String Repertoire

The repertoire of a character set is the collection of characters in the set.

As of MySQL 5.1.21, string expressions have a repertoire attribute, which can have two values:

The ASCII range is a subset of UNICODE range, so a string with ASCII repertoire can be converted safely without loss of information to the character set of any string with UNICODE repertoire or to a character set that is a superset of ASCII. (All MySQL character sets are supersets of ASCII with the exception of swe7, which reuses some punctuation characters for Swedish accented characters.) The use of repertoire enables character set conversion in expressions for many cases where MySQL would otherwise return an illegal mix of collations error.

The following discussion provides examples of expressions and their repertoires, and describes how the use of repertoire changes string expression evaluation: