复制After an upgrade to MySQL 4.1,置字 the statement fails: mysql> SELECT SUBSTRING_INDEX(USER(),@,1); ERROR 1267 (HY000): Illegal mix of collations (utf8_general_ci,IMPLICIT) and (latin1_swedish_ci,COERCIBLE) for operation substr_index The reason this occurs is that usernames are stored using UTF8 (see section 11.6 UTF8 for Metadata). As a result, the USER() function and the literal string @ have different character sets (and thus different collations): mysql> SELECT COLLATION(USER()), COLLATION(@); +-------------------+-------------------+ | COLLATION(USER()) | COLLATION(@) | +-------------------+-------------------+ | utf8_general_ci | latin1_swedish_ci | +-------------------+-------------------+ One way to deal with this is to tell MySQL to interpret the literal string as utf8: mysql> SELECT SUBSTRING_INDEX(USER(),_utf8@,1); +------------------------------------+ | SUBSTRING_INDEX(USER(),_utf8@,1) | +------------------------------------+ | root | +------------------------------------+ Another way is to change the connection character set and collation to utf8. You can do that with SET NAMES utf8 or by setting the character_set_connection and collation_connection system variables directly. 1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.28.29.30.31.32.33.34.35.36.37.38.39. |
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